We evaluated whether the dodecylamine derivative of hydroxocobalamin acts as a potent inhibitor of cobalamin-dependent enzymes in an African green monkey kidney cell, COS-7. When the dodecylamine derivative (1.0 μmol...We evaluated whether the dodecylamine derivative of hydroxocobalamin acts as a potent inhibitor of cobalamin-dependent enzymes in an African green monkey kidney cell, COS-7. When the dodecylamine derivative (1.0 μmol/L) did not show any cytotoxicity in the cultured cells, the derivative could not affect methylmalonyl-CoA mutase (holo-enzyme) activity, but significantly inhibit methionine synthase (holo-enzyme) activity in the cell homogenates of COS-7 grown in 1.0 μmol/L hydroxocobalamin-supplemented medium. An immunoblot analysis indicated that the dodecylamine derivative could not decrease the protein level of methionine synthase, but significantly inhibit the enzyme activity.展开更多
Cobalamin uptake into cells is mediated by the CD320 receptor for transcobalamin-bound cobalamin. Optimum receptor expression is associated with proliferating cells and therefore, in many cancers this receptor express...Cobalamin uptake into cells is mediated by the CD320 receptor for transcobalamin-bound cobalamin. Optimum receptor expression is associated with proliferating cells and therefore, in many cancers this receptor expression is up regulated. Delivering drugs or toxins via this receptor provides increased targeting to cancer cells while minimizing toxicity to the normal tissues. Saporin conjugated monoclonal antibodies to the extracellular domain of TCblR were effectively internalized to deliver a toxic dose of Saporin to some cancer cell lines propagating in culture. Antibody concentration of 2.5 nM was effective in producing optimum inhibition of cell proliferation. The cytotoxic effect of mAb-Saporin appears to be dictated primarily by the level of receptor expression and therefore normal primary cells expressing low levels of CD320 were spared while tumor cell lines with higher CD320 expression were destroyed. Targeting the pathway for cellular uptake of vitamin B12 via the CD320 receptor with toxin-antibody conjugates appears to be a viable treatment strategy for certain cancers that over expresses this receptor.展开更多
We read with great interest the excellent review by Wong et al on extra intestinal manifestations of Helicobacter pylori(H.pylori) infection published in the journal.This is a well-documented and structured review.How...We read with great interest the excellent review by Wong et al on extra intestinal manifestations of Helicobacter pylori(H.pylori) infection published in the journal.This is a well-documented and structured review.However,I believe that Wong et al failed to report the relationship between H.pylori infection and cobalamin.展开更多
Background:The present study was undertaken to investigate the clinical characteristics of hemolytic uremic syndrome(HUS)secondary to cobalamin C disorder(cbl-C disorder).Methods:We reviewed retrospectively the medica...Background:The present study was undertaken to investigate the clinical characteristics of hemolytic uremic syndrome(HUS)secondary to cobalamin C disorder(cbl-C disorder).Methods:We reviewed retrospectively the medical records of 3 children with HUS secondary to cbl-C disorder who had been treated between April 1,2009 and October 31,2013.Results:The 3 patients with HUS secondary to cbl-C disorder presented with progressive hemolytic anemia,acute renal failure,thrombocytopenia,poor feeding,and failure to thrive.Two of the 3 patients once had high blood pressure.The mutations of c.609G>A(P.W203X),c.217C>T(p.R73X)and c.365A>T(p.H122L)in the methylmalonic aciduria(cobalamin deficiency)cbl-C type,with homocystinuria gene were detected in the 3 patients.In these patients the levels of lactate dehydrogenase and homocysteine in serum were elevated and the level of methylmalonic acid(MMA)in urine was also elevated.After treatment with hydroxocobalamin,2 patients were discharged with no obvious abnormal growth and neurological development and 1 patient died of multiple organ failure.Conclusions:The results of this study demonstrated that cbl-C disorder should be investigated in any child presenting with HUS.The high concentrations of homocysteine and MMA could be used for timely recognization of the disease.Once the high levels of plasma homocystein and/or plasma or urine MMA are detected,the treatment with parenteral hydroxocobalamin should be prescribed immediately.The early diagnosis and treatment would contribute to the good prognosis of the disease.展开更多
Two new coenzyme B12 analogues, 2’,5’-dideoxycytidylcobalamin (2a) and 2’,5’-dide-oxyuridinylcobalamin (2b), and two others, 2’,5’-dideoxyadenosylcobalamin (2c), and 5’-deoxy-thymidylcobalamin (2d) were prepare...Two new coenzyme B12 analogues, 2’,5’-dideoxycytidylcobalamin (2a) and 2’,5’-dide-oxyuridinylcobalamin (2b), and two others, 2’,5’-dideoxyadenosylcobalamin (2c), and 5’-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.展开更多
In this paper,the influence of two typical ionic impurities(Na_(+)and Mg_(2+))is investigated with the focused beam reflectance measurement(FBRM)technique.In this system,the on-line FBRM is used as a tool for monitori...In this paper,the influence of two typical ionic impurities(Na_(+)and Mg_(2+))is investigated with the focused beam reflectance measurement(FBRM)technique.In this system,the on-line FBRM is used as a tool for monitoring the crystallization process of cobalamin by measuring the chord length distribution of particles and the particle counts.It is noted that impurity Mg_(2+)has a more significant effect than Na_(2+)in crystal growth of the whole crystallization process.From the microscopic observation of crystals,Mg_(2+)has an obvious effect on the crystal habit,while Na_(2+)has little effect.In addition,the crystal habit changes can be monitored by particle vision measurement(PVM).Understanding these effects is helpful to aid optimization and improve process control.展开更多
Cobalamin is an essential human vitamin widely used in the pharmaceutical,food,and feed additive industries and currently produced by bacteria or archaea.Ensifer adhaerens HY-1 is an industrial strain that also produc...Cobalamin is an essential human vitamin widely used in the pharmaceutical,food,and feed additive industries and currently produced by bacteria or archaea.Ensifer adhaerens HY-1 is an industrial strain that also produces cobalamin.However production outputs are poor and the specific synthesis pathways require characterization.In this study,the whole genome sequence of E.adhaerens HY-1 was generated and annotated,and genes associated with cobalamin biosynthesis were identified.Then,three genes,CobSV,CobQ,and CobW were identified as the most efficient ones for enhancing cobalamin synthesis.By transcriptome sequencing of E.adhaerens HY-1 cells at different growth stages,65 endogenous promoters with different gradient strengths were identified.After combined expression of different strength promoters and key genes,a high cobalamin-producing recombinant strain,‘hmm’(genotype:PmetH-CobSV-PibpA-CobQ-Pmdh-CobW),was generated.Cobalamin production was 143.8 mg/L in shaking flasks,which was 41.0%higher than the original strain.Cobalamin production was further enhanced to 171.2 mg/L using fed-batch fermentation.Importantly,our data and novel approach provide important references for the analysis of cobalamin synthesis and other metabolites in complex metabolic pathways.展开更多
Dinoflagellates are responsible for most marine harmful algal blooms (HABs) and play vital roles in many ocean processes.More than 90% of dinoflagellates are vitamin B_(12) auxotrophs and that B_(12) availability can ...Dinoflagellates are responsible for most marine harmful algal blooms (HABs) and play vital roles in many ocean processes.More than 90% of dinoflagellates are vitamin B_(12) auxotrophs and that B_(12) availability can control dinoflagellate HABs,yet the genetic basis of B_(12) auxotrophy in dinoflagellates in the framework of the ecology of dinoflagellates and particularly HABs,which was the objective of this work.Here,we investigated the presence,phylogeny,and transcription of two methionine synthase genes(B_(12)-dependent metH and B_(12)-independent metE)via searching and assembling transcripts and genes from transcriptomic and genomic databases,cloning 38 cDNA isoforms of the two genes from 14 strains of dinoflagellates,measuring the expression at different scenarios of B_(12),and comprehensive phylogenetic analyses of more than 100 organisms.We found that 1)metH was present in all 58 dinoflagellates accessible and metE was present in 40 of 58 species,2)all metE genes lacked N-terminal domains,3)metE of dinoflagellates were phylogenetically distinct from other known metE genes,and 4)expression of metH in dinoflagellates was responsive to exogenous B_(12) levels while expression of metE was not responding as that of genuine metE genes.We conclude that most,hypothetically all,dinoflagellates have either non-functional metE genes lacking N-terminal domain for most species,or do not possess metE for other species,which provides the genetic basis for the widespread nature of B_(12) auxotrophy in dinoflagellates.The work elucidated a fundamental aspect of the nutritional ecology of dinoflagellates.展开更多
文摘We evaluated whether the dodecylamine derivative of hydroxocobalamin acts as a potent inhibitor of cobalamin-dependent enzymes in an African green monkey kidney cell, COS-7. When the dodecylamine derivative (1.0 μmol/L) did not show any cytotoxicity in the cultured cells, the derivative could not affect methylmalonyl-CoA mutase (holo-enzyme) activity, but significantly inhibit methionine synthase (holo-enzyme) activity in the cell homogenates of COS-7 grown in 1.0 μmol/L hydroxocobalamin-supplemented medium. An immunoblot analysis indicated that the dodecylamine derivative could not decrease the protein level of methionine synthase, but significantly inhibit the enzyme activity.
文摘Cobalamin uptake into cells is mediated by the CD320 receptor for transcobalamin-bound cobalamin. Optimum receptor expression is associated with proliferating cells and therefore, in many cancers this receptor expression is up regulated. Delivering drugs or toxins via this receptor provides increased targeting to cancer cells while minimizing toxicity to the normal tissues. Saporin conjugated monoclonal antibodies to the extracellular domain of TCblR were effectively internalized to deliver a toxic dose of Saporin to some cancer cell lines propagating in culture. Antibody concentration of 2.5 nM was effective in producing optimum inhibition of cell proliferation. The cytotoxic effect of mAb-Saporin appears to be dictated primarily by the level of receptor expression and therefore normal primary cells expressing low levels of CD320 were spared while tumor cell lines with higher CD320 expression were destroyed. Targeting the pathway for cellular uptake of vitamin B12 via the CD320 receptor with toxin-antibody conjugates appears to be a viable treatment strategy for certain cancers that over expresses this receptor.
文摘We read with great interest the excellent review by Wong et al on extra intestinal manifestations of Helicobacter pylori(H.pylori) infection published in the journal.This is a well-documented and structured review.However,I believe that Wong et al failed to report the relationship between H.pylori infection and cobalamin.
基金supported by a grant from the Special Program for Clinical Research of the Beijing Municipal Commission of Science and Technology and WU JIE PING Medical Foundation,China(Grant Z121107005112008)
文摘Background:The present study was undertaken to investigate the clinical characteristics of hemolytic uremic syndrome(HUS)secondary to cobalamin C disorder(cbl-C disorder).Methods:We reviewed retrospectively the medical records of 3 children with HUS secondary to cbl-C disorder who had been treated between April 1,2009 and October 31,2013.Results:The 3 patients with HUS secondary to cbl-C disorder presented with progressive hemolytic anemia,acute renal failure,thrombocytopenia,poor feeding,and failure to thrive.Two of the 3 patients once had high blood pressure.The mutations of c.609G>A(P.W203X),c.217C>T(p.R73X)and c.365A>T(p.H122L)in the methylmalonic aciduria(cobalamin deficiency)cbl-C type,with homocystinuria gene were detected in the 3 patients.In these patients the levels of lactate dehydrogenase and homocysteine in serum were elevated and the level of methylmalonic acid(MMA)in urine was also elevated.After treatment with hydroxocobalamin,2 patients were discharged with no obvious abnormal growth and neurological development and 1 patient died of multiple organ failure.Conclusions:The results of this study demonstrated that cbl-C disorder should be investigated in any child presenting with HUS.The high concentrations of homocysteine and MMA could be used for timely recognization of the disease.Once the high levels of plasma homocystein and/or plasma or urine MMA are detected,the treatment with parenteral hydroxocobalamin should be prescribed immediately.The early diagnosis and treatment would contribute to the good prognosis of the disease.
基金Project supported by the National Natural Science Foundation of China.
文摘Two new coenzyme B12 analogues, 2’,5’-dideoxycytidylcobalamin (2a) and 2’,5’-dide-oxyuridinylcobalamin (2b), and two others, 2’,5’-dideoxyadenosylcobalamin (2c), and 5’-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.
基金the National Key Technologies R&D Program for financial support(No.2007BAI46B04).
文摘In this paper,the influence of two typical ionic impurities(Na_(+)and Mg_(2+))is investigated with the focused beam reflectance measurement(FBRM)technique.In this system,the on-line FBRM is used as a tool for monitoring the crystallization process of cobalamin by measuring the chord length distribution of particles and the particle counts.It is noted that impurity Mg_(2+)has a more significant effect than Na_(2+)in crystal growth of the whole crystallization process.From the microscopic observation of crystals,Mg_(2+)has an obvious effect on the crystal habit,while Na_(2+)has little effect.In addition,the crystal habit changes can be monitored by particle vision measurement(PVM).Understanding these effects is helpful to aid optimization and improve process control.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(32021005)the National Science Fund for Excellent Young Scholars(21822806).
文摘Cobalamin is an essential human vitamin widely used in the pharmaceutical,food,and feed additive industries and currently produced by bacteria or archaea.Ensifer adhaerens HY-1 is an industrial strain that also produces cobalamin.However production outputs are poor and the specific synthesis pathways require characterization.In this study,the whole genome sequence of E.adhaerens HY-1 was generated and annotated,and genes associated with cobalamin biosynthesis were identified.Then,three genes,CobSV,CobQ,and CobW were identified as the most efficient ones for enhancing cobalamin synthesis.By transcriptome sequencing of E.adhaerens HY-1 cells at different growth stages,65 endogenous promoters with different gradient strengths were identified.After combined expression of different strength promoters and key genes,a high cobalamin-producing recombinant strain,‘hmm’(genotype:PmetH-CobSV-PibpA-CobQ-Pmdh-CobW),was generated.Cobalamin production was 143.8 mg/L in shaking flasks,which was 41.0%higher than the original strain.Cobalamin production was further enhanced to 171.2 mg/L using fed-batch fermentation.Importantly,our data and novel approach provide important references for the analysis of cobalamin synthesis and other metabolites in complex metabolic pathways.
基金edge the financial support from the National Natural Science Foundation of China(Grant No.41776125)the Key Deployment Project of Centre for Ocean Mega-Research of Science,Chinese Academy of Sciences(Grant No.COMS2019Q09)+3 种基金the Science&Technology Basic Resources Investigation Program of China(Grant No.2018FY100200)National Natural Science Foundation of China(Grants Nos.41976134 and 61533011)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(Grant No.2018SDKJ0504-2)supported by the Chicago Community Trust.
文摘Dinoflagellates are responsible for most marine harmful algal blooms (HABs) and play vital roles in many ocean processes.More than 90% of dinoflagellates are vitamin B_(12) auxotrophs and that B_(12) availability can control dinoflagellate HABs,yet the genetic basis of B_(12) auxotrophy in dinoflagellates in the framework of the ecology of dinoflagellates and particularly HABs,which was the objective of this work.Here,we investigated the presence,phylogeny,and transcription of two methionine synthase genes(B_(12)-dependent metH and B_(12)-independent metE)via searching and assembling transcripts and genes from transcriptomic and genomic databases,cloning 38 cDNA isoforms of the two genes from 14 strains of dinoflagellates,measuring the expression at different scenarios of B_(12),and comprehensive phylogenetic analyses of more than 100 organisms.We found that 1)metH was present in all 58 dinoflagellates accessible and metE was present in 40 of 58 species,2)all metE genes lacked N-terminal domains,3)metE of dinoflagellates were phylogenetically distinct from other known metE genes,and 4)expression of metH in dinoflagellates was responsive to exogenous B_(12) levels while expression of metE was not responding as that of genuine metE genes.We conclude that most,hypothetically all,dinoflagellates have either non-functional metE genes lacking N-terminal domain for most species,or do not possess metE for other species,which provides the genetic basis for the widespread nature of B_(12) auxotrophy in dinoflagellates.The work elucidated a fundamental aspect of the nutritional ecology of dinoflagellates.
