Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cl...Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.展开更多
Mitogen-activated protein kinase(MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly contro...Mitogen-activated protein kinase(MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly controlled, but the underlying mechanism remains unclear. Here, we identified Arabidopsis CPL1(C-terminal domain phosphatase-like 1)as a negative regulator of microbe-associated molecular pattern(MAMP)-triggered immunity via a forward-genetic screen. Disruption of CPL1 significantly enhanced plant resistance to Pseudomonas pathogens induced by the bacterial peptide fg22. Furthermore, fg22-induced MPK3/MPK4/MPK6 phosphorylation was dramatically elevated in cpl1 mutants but severely impaired in CPL1 overexpression lines, suggesting that CPL1 might interfere with fg22-induced MAPK activation. Indeed, CPL1 directly interacted with MPK3 and MPK6, as well as the upstream MKK4 and MKK5. A firefy luciferase-based complementation assay indicated that the interaction between MKK4/MKK5 and MPK3/MPK6 was significantly reduced in the presence of CPL1. These results suggest that CPL1 plays a novel regulatory role in suppressing MAMP-induced MAPK cascade activation and MAMP-triggered immunity to bacterial pathogens.展开更多
Dear Editor,Yellow fever(YF),a mosquito-borne flavivirus disease,is endemic in tropical areas of Africa and Central and South America.YF is transmitted via the bite of infected Aedes aegypti or Haemogogus mosquitoes a...Dear Editor,Yellow fever(YF),a mosquito-borne flavivirus disease,is endemic in tropical areas of Africa and Central and South America.YF is transmitted via the bite of infected Aedes aegypti or Haemogogus mosquitoes and mainly affects humans and nonhuman primates.The clinical course of infection in humans shows a wide spectrum of severity including no symptoms,mild illness,and severe disease including展开更多
Amino acids are basic units to construct a protein with the assistance of various interactions.During this building process,steric hindrance derived from amino acid side groups or side chains is a factor that could no...Amino acids are basic units to construct a protein with the assistance of various interactions.During this building process,steric hindrance derived from amino acid side groups or side chains is a factor that could not be ignored.In this contribution,adsorption behaviors of C-terminal amino acid derivatives with amino acid residues fused in 3,4,9,10-perylenetetracarboxylic dianhydride were investigated by scanning tunneling microscopy(STM)and density functional theory(DFT)calculations at various liquid/solid interfaces.STM results at 1-phenyloctane/HOPG interface show that N,N'-3,4,9,10-perylenedicarboximide(GP)and N,N'-methyl-3,4,9,10-perylenedicarboximide(AP)formed linear and herringbone structures,respectively.The driving force could be attributed to different H-bonding sites induced by steric hindrance at side groups.N,N'-Benzyl-3,4,9,10-perylenedicarboximide(PP)generates both linear and herringbone structures because steric hindrance changes the H-bonding sites between PP molecules,whereas N,N'-isopropyl-3,4,9,10-perylenedicarboximide(LP)failed to be imaged because of strong steric hindrance coming from larger side group.To further investigate the impact of steric hindrance,we utilized octanoic acid(OA)as solvent to capture the adsorption details of LP and PP.We found that OA molecules drag PP and LP molecules in a different direction to generate linear structure,impeding the molecular rotation.The structure–solvent relationship shows that the steric hindrance is brought by the large side group,which makes it easier to recognize OA molecules at the interface.These results demonstrate that steric effect plays a significant role in altering interaction sites of the compounds during the adsorption process at the liquid/solid interface.展开更多
BACKGROUND Intracranial and extracranial artery stenosis is associated with cerebral infarction.Vascular calcification and atherosclerosis are the main causes of stenosis and major risk factors for cardiovascular and ...BACKGROUND Intracranial and extracranial artery stenosis is associated with cerebral infarction.Vascular calcification and atherosclerosis are the main causes of stenosis and major risk factors for cardiovascular and cerebrovascular events in patients with type 2 diabetes mellitus(T2DM).Bone turnover biomarkers(BTMs)are associated with vascular calcification,atherosclerosis,glucose,and lipid metabolism.AIM To investigate the association of circulating BTM levels with severe intracranial and extracranial artery stenosis in patients with T2DM.METHODS For this cross-sectional study including 257 T2DM patients,levels of the BTMs serum osteocalcin(OC),C-terminal cross-linked telopeptide of type I collagen(CTX),and procollagen type I N-peptide were measured by electrical chemiluminescent immunoassay,and artery stenosis was assessed by color Doppler and transcranial Doppler.Patients were grouped according to the existence and location(intracranial vs.extracranial)of artery stenosis.Correlations between BTM levels,previous stroke,stenosis location,and glucose and lipid metabolism were analyzed.RESULTS T2DM patients with severe artery stenosis had a higher frequency of previous stroke and levels of all three tested BTMs(all P<0.05)than patients without.Some differences in OC and CTX levels were observed according to the location of artery stenosis.Significant associations were also observed between BTM levels and some glucose and lipid homeostasis parameters.On multivariate logistic regression analysis,all BTMs were significant predictors of artery stenosis in T2DM patients with and without adjustment for confounding factors(all P<0.001),and receiver operating characteristic curve analysis demonstrated the ability of BTM levels to predict artery stenosis in T2DM patients.CONCLUSION BTM levels were found to be independent risk factors for severe intracranial and extracranial artery stenosis and were differentially associated with glucose and lipid metabolism in patients with T2DM.Therefore,BTMs may be promising biomarkers and potential therapeutic targets for artery stenosis.展开更多
This paper reported the identification of the primary structure of two peptides using nanoelectrospray tandem mass spectrometry(Nano-ESI MS/MS).Firstly,the relative molecular mass of two peptides were determined in ES...This paper reported the identification of the primary structure of two peptides using nanoelectrospray tandem mass spectrometry(Nano-ESI MS/MS).Firstly,the relative molecular mass of two peptides were determined in ESI-TOF MS mode.Then fragmentation ions were obtained by selecting [M+2H]2+ ion using tandem mass spectrometry(MS/MS).Finally,the primary structure of triptorelin is determined to be E’HWSYWLRPG’,of which the N-terminal is pyroglutamic acid (E’) and the C-termianl is glycinamide (G’).The primary structure of unknown peptide was identified to be T’VSP VWLPPSVY by sequence docking method,of which the N-terminal occurs threonine phosphorylation (T’) and the foruth proline is added with sodium ion (P).The data suggested that electrospray Tandem mass spectrometry technique have obvious advantage in analyzing the full sequence of modified or unknown peptides.展开更多
C-terminal sequencing is important for characterized the primary structure of protein and polypeptides and it must do for quality control of recombination protein drugs.A method of MALDI-TOF-TOF-MS with in source deca...C-terminal sequencing is important for characterized the primary structure of protein and polypeptides and it must do for quality control of recombination protein drugs.A method of MALDI-TOF-TOF-MS with in source decay(ISD) to measure C-terminal sequence of protein was established.This method was applied successfully to measure C-terminal sequence of Neuregulin,TP-Ⅱ,ubiquitin,and myoglobin,respectively and 10,24,24 and 36 amino acid residue of C-terminal were measured.展开更多
C-terminal sequence is important for the function of a protein.C-terminal sequencing is necessary for structure identification of recombinant drugs.In this paper,a new method based on CNBr cleavage coupled with ESI MS...C-terminal sequence is important for the function of a protein.C-terminal sequencing is necessary for structure identification of recombinant drugs.In this paper,a new method based on CNBr cleavage coupled with ESI MS/MS was established and successfully applied to C-terminal sequence analysis of recombinant human TNFR and neuregulin.Results showed,C-terminal sequences with 19 and 11 amino acids were identified respectively.This new method was sensitive,reproducible and useful for C-terminal sequence analysis of recombinant proteins.展开更多
BACKGROUND: The long-term use of nucleos(t)ide analogues causes drug resistance and mutations in the HBV reverse transcriptase(RT) region of the polymerase gene. The RT region overlaps the HBV surface gene(S gene) and...BACKGROUND: The long-term use of nucleos(t)ide analogues causes drug resistance and mutations in the HBV reverse transcriptase(RT) region of the polymerase gene. The RT region overlaps the HBV surface gene(S gene) and therefore, the mutations in the RT region simultaneously modify S gene sequence. Certain mutations in the RT region bring about truncated S proteins because the corresponding changed S gene encodes a stop codon which results in the loss of a large portion of the C-terminal hydrophobic region of HBV surface protein. The rtA181T/sW172*, rtM204I/sW196* and rtV191I/sW182* are the most frequently reported drug-resistant mutations with C-terminal truncation, these mutations have oncogenic potential.DATA SOURCES: Pub Med and Web of Science were searched using terms: "hepatitis B virus", "HBV drug resistance mutation", "HBV surface protein", "HBV truncation", "hepatocellular carcinoma", "rtA181T/sW172*", "rt M204I/sW196*", "rtV191I/sW182*", and relevant articles published in English in the past decades were reviewed.RESULTS: The rtA181T/sW172* and rtV191I/sW182* mutants occurred more frequently than the rtM204I/sW196* mutant both in chronic hepatitis B patients and the HBV-related hepatocellular carcinoma tissues. Although these mutations occur naturally, nucleos(t)ide analogues therapy is the main driving force. These mutations may exist alone or coexist with other HBV mutations. All these three mutants impair the virion secretion and result in HBV surface protein retention and serum HBV DNA level reduction. These mutations possess potential carcinogenic properties. The three mutations are resistant to more than one nucleos(t)ide analogue and therefore, it is difficult to treat the patients with the truncated mutations.CONCLUSIONS: Nucleos(t)ide analogues induce drug resistance and HBV S gene truncated mutations. These mutations have potential carcinogenesis.展开更多
AIM:To investigate the postprandial response of bone turnover markers in patients with Crohn’s disease(CD).METHODS:Fifty nine patients with CD aged 38±14years,and 45 healthy individuals matched for age and body ...AIM:To investigate the postprandial response of bone turnover markers in patients with Crohn’s disease(CD).METHODS:Fifty nine patients with CD aged 38±14years,and 45 healthy individuals matched for age and body mass index were included in the study.All participants underwent an oral glucose tolerance test(OGTT)after an overnight fast and serum levels of the bone resorption marker C-terminal crosslinking telopeptide of type?Ⅰ?collagen(CTX-Ⅰ)and the bone formation marker procollagen type?Ⅰ?N propeptide were measured.Activity of the disease was assessed by calculation of the Crohn’s disease activity index(CDAI).RESULTS:Serum CTX-I was significantly higher in patients compared to controls(CTX-I:453±21 pg/mL vs 365±25 pg/mL,P=0.008),and values were significantly correlated with the activity of the disease(r=0.435,P=0.001).Results from OGTT-induced suppression of CTX-I showed two different trends.Patients with more active disease(assessed as CDAI>150)had a more excessive suppression of CTX-I compared to controls(55%vs 43%P<0.001),while patients on remission(assessed as CDAI<150)demonstrated an attenuated CTX-I suppression(30%vs 43%P<0.001).In line with this,CTX-I suppression after oral glucose load was significantly correlated with the activity of the disease(r=0.913,P<0.001).CONCLUSION:The physiological skeletal response of postprandial suppression of bone resorption is maintained in patients with CD and is strongly dependent to the activity of the disease.展开更多
Esophageal cancer is the second most common type of cancer after lung carcinoma in the state of Jammu and Kashmir(J&K).The understanding of genetics in Esophageal cancer development is poor in the state.Genome wid...Esophageal cancer is the second most common type of cancer after lung carcinoma in the state of Jammu and Kashmir(J&K).The understanding of genetics in Esophageal cancer development is poor in the state.Genome wide association studies(GWAS)has proved to be unsurpassed tool in identification of new loci associated with different cancers.GWAS in Chinese population has identified SNP rs2294693 present in UNC5CL(UNC-5 Family C-Terminal like)to be associated with non-cardia gastric cancer.We performed a case control association study and genotyped the SNP rs2294693 using Taqman allele discrimination assay in 566 individuals(166 esophageal cancer patients and 400 controls)belonging to the J&K population.A statistically significant protective association with allelic odds ratio of 0.73(0.56–0.94 at 95%CI)and p value=0.016 was observed.This is the first study in relation to esophageal cancer in the Jammu and Kashmir population,so far it has been studied in association with gastric carcinoma in the Chinese population only.The results indicate that the polymorphism rs2294693 is associated with esophageal cancer susceptibility and the mutant(T)allele might be a protective factor for esophageal cancer among Jammu and Kashmir population.Further the functional characterization of the variation is also warranted.展开更多
Myelodysplasia syndrome 1 (MDS1) and Ecotropic viral integration site 1 (EVI1) complex (MECOM) locus encode multiple isoforms of the EVI1 protein that are essential for normal vertebrate development and when inappropr...Myelodysplasia syndrome 1 (MDS1) and Ecotropic viral integration site 1 (EVI1) complex (MECOM) locus encode multiple isoforms of the EVI1 protein that are essential for normal vertebrate development and when inappropriately expressed play a significant role in malignancy and in particular leukaemias. However, the function of individual EVI1 isoforms is not fully understood. Recently, EVI1 or PRDM3, which is structurally closely related to the brown adipose tissue determining factor PRDM16, was shown to be required for differentiation of adipocytes. In this study, we show that 3T3-L1 preadipocytes sustain expression of all Evi1 isoforms examined, including Mds1-Evi1, Evi1FL, Evi1Δ324, Evi1FL + 9 and Evi1Δ105 throughout the adipogenesis differentiation programme. We also show that differentiation markers are enhanced by enforced expression of either Evi1, Evi1FL + 9 or Evi1Δ105 isoforms. Interestingly 3T3-L1 differentiation markers are also moderately enhanced by enforced expression of Evi1Δ324, which lacks part of the N-ter-minal zinc finger domain (ZF1), demonstrating a biological activity for this particular isoform. Enforced expression of an Evi1 mutant lacking C-terminal binding protein (CtBP) co-repressor protein binding activity fails to stimulate 3T3-L1 differentiation markers and may have dominant negative activity, causing partial inhibition of this developmental programme. These studies show that multiple EVI1 isoforms are expressed in adipocytes and can stimulate adipogenic markers in a manner that is partially independent of the ZF1 DNA binding domain but fully dependent upon interaction with co-repressor CtBP proteins.展开更多
N-terminal and C-terminal analysis of genetic engineering recombinant proteins are two criteria of determining their primary structure. The N-terminal sequencing relies heavily upon the Edman degradation method, which...N-terminal and C-terminal analysis of genetic engineering recombinant proteins are two criteria of determining their primary structure. The N-terminal sequencing relies heavily upon the Edman degradation method, which has been automated with commercially available sequencers. The maximum number of residues which may be placed in sequence in a single run is about 50. In the present decade, improvements in this technique made it展开更多
Human maltase-glucoamylase(MGAM)hydrolyzes linear alpha-1,4-linked oligosaccharide substrates,playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 di...Human maltase-glucoamylase(MGAM)hydrolyzes linear alpha-1,4-linked oligosaccharide substrates,playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity.The amino-and carboxyl-terminal portions of MGAM(MGAM-N and MGAM-C)carry out the same catalytic reaction but have different substrate specificities.In this study,we report crystal structures of MGAM-C alone at a resolution of 3.1Å,and in complex with its inhibitor acarbose at a resolution of 2.9Å.Structural studies,combined with biochemical analysis,revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites(+2 and+3 subsites),accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N.Moreover,we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides.These results provide important information for understanding the substrate specificity of alphaglucosidases during the process of terminal starch digestion,and for designing more efficient drugs to control type 2 diabetes or obesity.展开更多
Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively...Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively. However, how these highly similar signal sequences confer the protein import specificity remains elusive. Here, we show that mitochondrial- or chloroplast-specific import involves two distinct steps, specificity determination and translocation across envelopes, which are mediated by the N-terminal regions and functionally interchangeable C-terminal regions, respectively, of transit peptides and presequences. A domain harboring multiple-arginine and hydrophobic sequence motifs in the N-terminal regions of presequences was identified as the mitochondrial specificity factor. The presence of this domain and the absence of arginine residues in the N-terminal regions of otherwise common targeting signals confers specificity of protein import into mitochondria and chloroplasts, respectively. AtToc159, a chloroplast import receptor, also contributes to determining chloroplast import specificity. We propose that common ancestral sequences were functionalized into mitochondrial- and chloroplast-specific signal sequences by the presence and absence, respectively, of multiple-arginine and hydrophobic sequence motifs in the N-terminal region.展开更多
The three-dimensional structure of trichosanthin at 2.7A resolution has been improved further, by refitting one of the C-terminal tails, adjusting 16 residues in the molecular surface regions, discarding some water mo...The three-dimensional structure of trichosanthin at 2.7A resolution has been improved further, by refitting one of the C-terminal tails, adjusting 16 residues in the molecular surface regions, discarding some water molecules with high B values, and adjusting weights during the further refinement. The R-factor has been reduced to 18.5% and the r.m.s deviations from ideal geometry are also improved. The structures of the two molecules in the monoclinic asymmetric unit and the only molecule in the orthorhombic asymmetric unit are compared with one another. The main-chain structures for most of the residues in the three molecules are substantially the same. However, the courses of the three C-terminal tails are completely different, and the intermolecular interactions resulting from the particular packing of the molecules in the crystals account for the differences. The strand Be-2 and the preceding B-turn in small domain show large r.m.s. deviations among the three molecules and they are also involved in展开更多
Directed peptides C-terminal modification enabled by the engineered biomolecular catalyst-peptide amidase 12 B has been achieved via computational protein engineering. The engineered enzyme exhibits great promising po...Directed peptides C-terminal modification enabled by the engineered biomolecular catalyst-peptide amidase 12 B has been achieved via computational protein engineering. The engineered enzyme exhibits great promising potential in the C-terminal modification of opioid peptides using prop-2-yn-1-amine(PYA) or prop-2-en-l-amine(PEA) as the nucleophile. A variety of opioid peptides could be readily functionalized at the C-terminal chain in high yield in a mild and selective manner. Notably, modified opioid peptides bearing alkynyl moiety could be further functionalized through well-established click reaction.展开更多
基金supported by grants from the National Natural Science Foundation of China(31772455)Natural Science Foundation of Jiangsu Province(BK20160336and BK20171214)+1 种基金Natural Science Foundation of College in Jiangsu Province(16KJB350004)Suzhou Science and Technology Development Project(SYN201504 and SNG2017045)
文摘Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.
基金supported by the National Natural Science Foundation of China (grant no. 31671991 to FC)。
文摘Mitogen-activated protein kinase(MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly controlled, but the underlying mechanism remains unclear. Here, we identified Arabidopsis CPL1(C-terminal domain phosphatase-like 1)as a negative regulator of microbe-associated molecular pattern(MAMP)-triggered immunity via a forward-genetic screen. Disruption of CPL1 significantly enhanced plant resistance to Pseudomonas pathogens induced by the bacterial peptide fg22. Furthermore, fg22-induced MPK3/MPK4/MPK6 phosphorylation was dramatically elevated in cpl1 mutants but severely impaired in CPL1 overexpression lines, suggesting that CPL1 might interfere with fg22-induced MAPK activation. Indeed, CPL1 directly interacted with MPK3 and MPK6, as well as the upstream MKK4 and MKK5. A firefy luciferase-based complementation assay indicated that the interaction between MKK4/MKK5 and MPK3/MPK6 was significantly reduced in the presence of CPL1. These results suggest that CPL1 plays a novel regulatory role in suppressing MAMP-induced MAPK cascade activation and MAMP-triggered immunity to bacterial pathogens.
基金supported by the National Natural Science Foundation of China(81702015)the National Key Plan for Scientific Research and Development of China(2016YFD0500300)+6 种基金the National Science and Technology Major Project(2017ZX10303403)supported by the Excellent Young Scientist Program of the NSFC(81622031)the Excellent Young Scientist Program of the Chinese Academy of Sciences(CAS)the Youth Innovation Promotion Association CAS(2015078)supported by the Young Elite Scientist Sponsorship Program by China Association for Science and Technology(CAST)(2016QNRC001)the Youth Innovation Promotion Association CAS(2017117)a leading principal investigator of the NSFC Innovative Research Group(81621091)
文摘Dear Editor,Yellow fever(YF),a mosquito-borne flavivirus disease,is endemic in tropical areas of Africa and Central and South America.YF is transmitted via the bite of infected Aedes aegypti or Haemogogus mosquitoes and mainly affects humans and nonhuman primates.The clinical course of infection in humans shows a wide spectrum of severity including no symptoms,mild illness,and severe disease including
基金supported by the Ministry of Science and Technology(No.2017YFA0205000)National Natural Science Foundation of China(Nos.21303024,21365003,21463003,51478123,21962003,21902033)+6 种基金the National Key Basic Research Program of China(No.2012CB933001)the Chinese Academy of Sciences(No.YZ201318)The jiangxi Provincial"Ganpo Talents 555 Projects",Jiangxi Provincial Education Department Fund(No.KJLD13080)Jiangxi Provincial Funds for Distinguished Young Scientists(No.20153BCB23001)Jjiangxi Provincial Project of Scientific and Technological Innovation Team(No.20152BCB24008)Jiangxi Province Youth Science Foundation Project(No.20192BAB216013)Science and Technology Project of Jiangxi Province Education Department(No.180775)are also gratefully acknowledged.
文摘Amino acids are basic units to construct a protein with the assistance of various interactions.During this building process,steric hindrance derived from amino acid side groups or side chains is a factor that could not be ignored.In this contribution,adsorption behaviors of C-terminal amino acid derivatives with amino acid residues fused in 3,4,9,10-perylenetetracarboxylic dianhydride were investigated by scanning tunneling microscopy(STM)and density functional theory(DFT)calculations at various liquid/solid interfaces.STM results at 1-phenyloctane/HOPG interface show that N,N'-3,4,9,10-perylenedicarboximide(GP)and N,N'-methyl-3,4,9,10-perylenedicarboximide(AP)formed linear and herringbone structures,respectively.The driving force could be attributed to different H-bonding sites induced by steric hindrance at side groups.N,N'-Benzyl-3,4,9,10-perylenedicarboximide(PP)generates both linear and herringbone structures because steric hindrance changes the H-bonding sites between PP molecules,whereas N,N'-isopropyl-3,4,9,10-perylenedicarboximide(LP)failed to be imaged because of strong steric hindrance coming from larger side group.To further investigate the impact of steric hindrance,we utilized octanoic acid(OA)as solvent to capture the adsorption details of LP and PP.We found that OA molecules drag PP and LP molecules in a different direction to generate linear structure,impeding the molecular rotation.The structure–solvent relationship shows that the steric hindrance is brought by the large side group,which makes it easier to recognize OA molecules at the interface.These results demonstrate that steric effect plays a significant role in altering interaction sites of the compounds during the adsorption process at the liquid/solid interface.
基金Supported by Beijing Municipal Hospital Management Center“Cultivation Plan”,No.PX2022032.
文摘BACKGROUND Intracranial and extracranial artery stenosis is associated with cerebral infarction.Vascular calcification and atherosclerosis are the main causes of stenosis and major risk factors for cardiovascular and cerebrovascular events in patients with type 2 diabetes mellitus(T2DM).Bone turnover biomarkers(BTMs)are associated with vascular calcification,atherosclerosis,glucose,and lipid metabolism.AIM To investigate the association of circulating BTM levels with severe intracranial and extracranial artery stenosis in patients with T2DM.METHODS For this cross-sectional study including 257 T2DM patients,levels of the BTMs serum osteocalcin(OC),C-terminal cross-linked telopeptide of type I collagen(CTX),and procollagen type I N-peptide were measured by electrical chemiluminescent immunoassay,and artery stenosis was assessed by color Doppler and transcranial Doppler.Patients were grouped according to the existence and location(intracranial vs.extracranial)of artery stenosis.Correlations between BTM levels,previous stroke,stenosis location,and glucose and lipid metabolism were analyzed.RESULTS T2DM patients with severe artery stenosis had a higher frequency of previous stroke and levels of all three tested BTMs(all P<0.05)than patients without.Some differences in OC and CTX levels were observed according to the location of artery stenosis.Significant associations were also observed between BTM levels and some glucose and lipid homeostasis parameters.On multivariate logistic regression analysis,all BTMs were significant predictors of artery stenosis in T2DM patients with and without adjustment for confounding factors(all P<0.001),and receiver operating characteristic curve analysis demonstrated the ability of BTM levels to predict artery stenosis in T2DM patients.CONCLUSION BTM levels were found to be independent risk factors for severe intracranial and extracranial artery stenosis and were differentially associated with glucose and lipid metabolism in patients with T2DM.Therefore,BTMs may be promising biomarkers and potential therapeutic targets for artery stenosis.
文摘This paper reported the identification of the primary structure of two peptides using nanoelectrospray tandem mass spectrometry(Nano-ESI MS/MS).Firstly,the relative molecular mass of two peptides were determined in ESI-TOF MS mode.Then fragmentation ions were obtained by selecting [M+2H]2+ ion using tandem mass spectrometry(MS/MS).Finally,the primary structure of triptorelin is determined to be E’HWSYWLRPG’,of which the N-terminal is pyroglutamic acid (E’) and the C-termianl is glycinamide (G’).The primary structure of unknown peptide was identified to be T’VSP VWLPPSVY by sequence docking method,of which the N-terminal occurs threonine phosphorylation (T’) and the foruth proline is added with sodium ion (P).The data suggested that electrospray Tandem mass spectrometry technique have obvious advantage in analyzing the full sequence of modified or unknown peptides.
文摘C-terminal sequencing is important for characterized the primary structure of protein and polypeptides and it must do for quality control of recombination protein drugs.A method of MALDI-TOF-TOF-MS with in source decay(ISD) to measure C-terminal sequence of protein was established.This method was applied successfully to measure C-terminal sequence of Neuregulin,TP-Ⅱ,ubiquitin,and myoglobin,respectively and 10,24,24 and 36 amino acid residue of C-terminal were measured.
文摘C-terminal sequence is important for the function of a protein.C-terminal sequencing is necessary for structure identification of recombinant drugs.In this paper,a new method based on CNBr cleavage coupled with ESI MS/MS was established and successfully applied to C-terminal sequence analysis of recombinant human TNFR and neuregulin.Results showed,C-terminal sequences with 19 and 11 amino acids were identified respectively.This new method was sensitive,reproducible and useful for C-terminal sequence analysis of recombinant proteins.
基金supported by a grant from the National Natural Science Foundation of China(81071363)
文摘BACKGROUND: The long-term use of nucleos(t)ide analogues causes drug resistance and mutations in the HBV reverse transcriptase(RT) region of the polymerase gene. The RT region overlaps the HBV surface gene(S gene) and therefore, the mutations in the RT region simultaneously modify S gene sequence. Certain mutations in the RT region bring about truncated S proteins because the corresponding changed S gene encodes a stop codon which results in the loss of a large portion of the C-terminal hydrophobic region of HBV surface protein. The rtA181T/sW172*, rtM204I/sW196* and rtV191I/sW182* are the most frequently reported drug-resistant mutations with C-terminal truncation, these mutations have oncogenic potential.DATA SOURCES: Pub Med and Web of Science were searched using terms: "hepatitis B virus", "HBV drug resistance mutation", "HBV surface protein", "HBV truncation", "hepatocellular carcinoma", "rtA181T/sW172*", "rt M204I/sW196*", "rtV191I/sW182*", and relevant articles published in English in the past decades were reviewed.RESULTS: The rtA181T/sW172* and rtV191I/sW182* mutants occurred more frequently than the rtM204I/sW196* mutant both in chronic hepatitis B patients and the HBV-related hepatocellular carcinoma tissues. Although these mutations occur naturally, nucleos(t)ide analogues therapy is the main driving force. These mutations may exist alone or coexist with other HBV mutations. All these three mutants impair the virion secretion and result in HBV surface protein retention and serum HBV DNA level reduction. These mutations possess potential carcinogenic properties. The three mutations are resistant to more than one nucleos(t)ide analogue and therefore, it is difficult to treat the patients with the truncated mutations.CONCLUSIONS: Nucleos(t)ide analogues induce drug resistance and HBV S gene truncated mutations. These mutations have potential carcinogenesis.
文摘AIM:To investigate the postprandial response of bone turnover markers in patients with Crohn’s disease(CD).METHODS:Fifty nine patients with CD aged 38±14years,and 45 healthy individuals matched for age and body mass index were included in the study.All participants underwent an oral glucose tolerance test(OGTT)after an overnight fast and serum levels of the bone resorption marker C-terminal crosslinking telopeptide of type?Ⅰ?collagen(CTX-Ⅰ)and the bone formation marker procollagen type?Ⅰ?N propeptide were measured.Activity of the disease was assessed by calculation of the Crohn’s disease activity index(CDAI).RESULTS:Serum CTX-I was significantly higher in patients compared to controls(CTX-I:453±21 pg/mL vs 365±25 pg/mL,P=0.008),and values were significantly correlated with the activity of the disease(r=0.435,P=0.001).Results from OGTT-induced suppression of CTX-I showed two different trends.Patients with more active disease(assessed as CDAI>150)had a more excessive suppression of CTX-I compared to controls(55%vs 43%P<0.001),while patients on remission(assessed as CDAI<150)demonstrated an attenuated CTX-I suppression(30%vs 43%P<0.001).In line with this,CTX-I suppression after oral glucose load was significantly correlated with the activity of the disease(r=0.913,P<0.001).CONCLUSION:The physiological skeletal response of postprandial suppression of bone resorption is maintained in patients with CD and is strongly dependent to the activity of the disease.
文摘Esophageal cancer is the second most common type of cancer after lung carcinoma in the state of Jammu and Kashmir(J&K).The understanding of genetics in Esophageal cancer development is poor in the state.Genome wide association studies(GWAS)has proved to be unsurpassed tool in identification of new loci associated with different cancers.GWAS in Chinese population has identified SNP rs2294693 present in UNC5CL(UNC-5 Family C-Terminal like)to be associated with non-cardia gastric cancer.We performed a case control association study and genotyped the SNP rs2294693 using Taqman allele discrimination assay in 566 individuals(166 esophageal cancer patients and 400 controls)belonging to the J&K population.A statistically significant protective association with allelic odds ratio of 0.73(0.56–0.94 at 95%CI)and p value=0.016 was observed.This is the first study in relation to esophageal cancer in the Jammu and Kashmir population,so far it has been studied in association with gastric carcinoma in the Chinese population only.The results indicate that the polymorphism rs2294693 is associated with esophageal cancer susceptibility and the mutant(T)allele might be a protective factor for esophageal cancer among Jammu and Kashmir population.Further the functional characterization of the variation is also warranted.
文摘Myelodysplasia syndrome 1 (MDS1) and Ecotropic viral integration site 1 (EVI1) complex (MECOM) locus encode multiple isoforms of the EVI1 protein that are essential for normal vertebrate development and when inappropriately expressed play a significant role in malignancy and in particular leukaemias. However, the function of individual EVI1 isoforms is not fully understood. Recently, EVI1 or PRDM3, which is structurally closely related to the brown adipose tissue determining factor PRDM16, was shown to be required for differentiation of adipocytes. In this study, we show that 3T3-L1 preadipocytes sustain expression of all Evi1 isoforms examined, including Mds1-Evi1, Evi1FL, Evi1Δ324, Evi1FL + 9 and Evi1Δ105 throughout the adipogenesis differentiation programme. We also show that differentiation markers are enhanced by enforced expression of either Evi1, Evi1FL + 9 or Evi1Δ105 isoforms. Interestingly 3T3-L1 differentiation markers are also moderately enhanced by enforced expression of Evi1Δ324, which lacks part of the N-ter-minal zinc finger domain (ZF1), demonstrating a biological activity for this particular isoform. Enforced expression of an Evi1 mutant lacking C-terminal binding protein (CtBP) co-repressor protein binding activity fails to stimulate 3T3-L1 differentiation markers and may have dominant negative activity, causing partial inhibition of this developmental programme. These studies show that multiple EVI1 isoforms are expressed in adipocytes and can stimulate adipogenic markers in a manner that is partially independent of the ZF1 DNA binding domain but fully dependent upon interaction with co-repressor CtBP proteins.
文摘N-terminal and C-terminal analysis of genetic engineering recombinant proteins are two criteria of determining their primary structure. The N-terminal sequencing relies heavily upon the Edman degradation method, which has been automated with commercially available sequencers. The maximum number of residues which may be placed in sequence in a single run is about 50. In the present decade, improvements in this technique made it
基金by the National Basic Research Program of China(973 Program)(Grant Nos.2007CB914301 and 2007CB 914803)the Natural Science Foundation of China(Grant Nos.30940015,30770428,21002052 and 31170684)the TBR Program(No.08QTPTJC 28200,08SYSYTC00200 and 10JCYB JC14300).
文摘Human maltase-glucoamylase(MGAM)hydrolyzes linear alpha-1,4-linked oligosaccharide substrates,playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity.The amino-and carboxyl-terminal portions of MGAM(MGAM-N and MGAM-C)carry out the same catalytic reaction but have different substrate specificities.In this study,we report crystal structures of MGAM-C alone at a resolution of 3.1Å,and in complex with its inhibitor acarbose at a resolution of 2.9Å.Structural studies,combined with biochemical analysis,revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites(+2 and+3 subsites),accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N.Moreover,we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides.These results provide important information for understanding the substrate specificity of alphaglucosidases during the process of terminal starch digestion,and for designing more efficient drugs to control type 2 diabetes or obesity.
文摘Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively. However, how these highly similar signal sequences confer the protein import specificity remains elusive. Here, we show that mitochondrial- or chloroplast-specific import involves two distinct steps, specificity determination and translocation across envelopes, which are mediated by the N-terminal regions and functionally interchangeable C-terminal regions, respectively, of transit peptides and presequences. A domain harboring multiple-arginine and hydrophobic sequence motifs in the N-terminal regions of presequences was identified as the mitochondrial specificity factor. The presence of this domain and the absence of arginine residues in the N-terminal regions of otherwise common targeting signals confers specificity of protein import into mitochondria and chloroplasts, respectively. AtToc159, a chloroplast import receptor, also contributes to determining chloroplast import specificity. We propose that common ancestral sequences were functionalized into mitochondrial- and chloroplast-specific signal sequences by the presence and absence, respectively, of multiple-arginine and hydrophobic sequence motifs in the N-terminal region.
文摘The three-dimensional structure of trichosanthin at 2.7A resolution has been improved further, by refitting one of the C-terminal tails, adjusting 16 residues in the molecular surface regions, discarding some water molecules with high B values, and adjusting weights during the further refinement. The R-factor has been reduced to 18.5% and the r.m.s deviations from ideal geometry are also improved. The structures of the two molecules in the monoclinic asymmetric unit and the only molecule in the orthorhombic asymmetric unit are compared with one another. The main-chain structures for most of the residues in the three molecules are substantially the same. However, the courses of the three C-terminal tails are completely different, and the intermolecular interactions resulting from the particular packing of the molecules in the crystals account for the differences. The strand Be-2 and the preceding B-turn in small domain show large r.m.s. deviations among the three molecules and they are also involved in
基金supported by the National Natural Science Foundation of China(No.31601412)the 100 Talent Program grant and Biological Resources Service Network Initiative(No.ZSYS-012)grant from the Chinese Academy of Sciences(No.SKT1604)
文摘Directed peptides C-terminal modification enabled by the engineered biomolecular catalyst-peptide amidase 12 B has been achieved via computational protein engineering. The engineered enzyme exhibits great promising potential in the C-terminal modification of opioid peptides using prop-2-yn-1-amine(PYA) or prop-2-en-l-amine(PEA) as the nucleophile. A variety of opioid peptides could be readily functionalized at the C-terminal chain in high yield in a mild and selective manner. Notably, modified opioid peptides bearing alkynyl moiety could be further functionalized through well-established click reaction.
