Phlorizin(PHL)is a natural compound with strong antioxidant properties mainly found in apples.In this paper,the interaction mechanism of PHL with pepsin and trypsin was comparatively evaluated by computer simulation,f...Phlorizin(PHL)is a natural compound with strong antioxidant properties mainly found in apples.In this paper,the interaction mechanism of PHL with pepsin and trypsin was comparatively evaluated by computer simulation,fluorescence spectra,circular dichroism(CD),and Fourier transform infrared(FT-IR)spectra at a molecular level.Fluorescence spectra showed that PHL quenches the pepsin/trypsin by static quenching.Thermodynamic parameters indicated that PHL binds to pepsin mainly through hydrogen bonds and van der Waals forces,and that of trypsin was electrostatic forces.The ground state complexes PHL and protease have a moderate affinity of 105 L/mol PHL binds more strongly to trypsin than to pepsin.CD and FT-IR spectra results showed that pepsin/trypsin decreased theβ-sheet content and slightly changed its secondary structure upon PHL.These experimental results are mutually verified with the predicted computer-aid simulation results.Upon PHL and trypsin binding,the antioxidant capacity of PHL was elevated.Nevertheless,the antioxidant capacity of PHL was decreased after binding to pepsin.This work elucidates the binding of PHL binding mechanisms to pepsin/trypsin and provides useful information for the digestion of PHL to improve the application of PHL in food processing.展开更多
Hispidin is a pyranone compound found in edible and medicinal mushrooms of the Phellinus and Inonotus genera.This investigation used fluorescence spectroscopy,UV absorption spectroscopy,and molecular docking to examin...Hispidin is a pyranone compound found in edible and medicinal mushrooms of the Phellinus and Inonotus genera.This investigation used fluorescence spectroscopy,UV absorption spectroscopy,and molecular docking to examine the interaction of hispidin with pepsin.The Stern-Volmer method was used to perform the fluorescence quenching measurements at different temperatures(298 K,303 K,and 310 K).According to the findings,hispidin induced a static quenching mechanism in pepsin that resulted in the creation of a hispidin-pepsin complex with binding constants(Ka)ranging from 9.56×10^(4) to 3.45×10^(5) L mol^(-1).The positive values ofΔH(84.6 kJ mol-1)andΔS(337.9 J mol^(-1) K^(-1))demonstrated that hydrophobic forces contributed to forming the hispidin-pepsin complex.The findings of UV-vis absorption,synchronous fluorescence,and 3D fluorescence spectraspectra demonstrated that hispidin altered the conformation and microenvironment of pepsin.According to the analysis of molecular docking,hispidin got into the pepsin's active cavity.The research clarifies the molecular mechanisms by which hispidin binds to pepsin and helps understand its possible biological activity in vivo.展开更多
By using the wastes fish skin of sturgeon processed as a raw material, a macromolecule biomaterial of collagen was extracted. Acid-soluble collagen(ASC) and pepsin-soluble collagen(PSC) were successfully isolated from...By using the wastes fish skin of sturgeon processed as a raw material, a macromolecule biomaterial of collagen was extracted. Acid-soluble collagen(ASC) and pepsin-soluble collagen(PSC) were successfully isolated from the skin of hybrid sturgeon with two extraction methods. The yields of ASC and PSC based on the wet weight of skin were 5.73 ± 0.11% and 10.26 ± 0.39%, respectively. The denaturation and melting points of ASC(26.83 ℃ and 110.49 ℃) and PSC(26.54 ℃ and 102.99 ℃) were assessed by Circular dichroism(CD) and Differential scanning calorimetry(DSC). ASC and PSC appeared to be dense sheet-like film linked by random-coiled filaments under scanning electron microscopy(SEM). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Fourier transform infrared spectroscopy(FTIR) confirmed that both the ASC and PSC were Type I collagen and maintained a complete triple helix structure. These results indicated that both ASC and PSC possessed good biological activity and could be widely used in medical biomaterials and other fields.展开更多
The pepsin and trypsin activities and some of the properties of the two enzymes of southern sheatfish larvae were studied. The results were as follows: the highest level of trypsin activity is in the foregut in all...The pepsin and trypsin activities and some of the properties of the two enzymes of southern sheatfish larvae were studied. The results were as follows: the highest level of trypsin activity is in the foregut in all measured tissues; from foregut to hindgut, trypsin activities decrease; the pH optimum of trypsin activity is pH9.0; the strongest pepsin activity is in the stomach; the proper density of haemoglobin for detecting pepsin activity is 1.0%. These data are useful in solving applied nutritional problems, such as the adequacy of artificial food to the digestive abilities of the fish.展开更多
To make more effective use of underutilized resources, pepsin-solubilized collagen (PSC) was successfully extracted from the skin of black carp (Mylopharyngdon piceus) with a yield of 45.7% based on dry weight. The PS...To make more effective use of underutilized resources, pepsin-solubilized collagen (PSC) was successfully extracted from the skin of black carp (Mylopharyngdon piceus) with a yield of 45.7% based on dry weight. The PSC comprising two identical α1-chains and one α2-chain with no disulfide bond was characterized as type I, and it contained 195 imino acid residues vs. 1000 amino acid residues. The collagen showed an absorption edge around 218 nm, which was lower than the maximum absorption wavelength of other PSC. The denaturation temperature of PSC was 25.6°C, which was lower than that of porcine collagen by approximately 11°C. The isoelectric point (pI) was estimated to be 8.23, and the collagen was soluble at an acidic pH as well as below 40 g/L NaCl. It is thought that the high yield and stability of PSC from the skin of black carp warrant its application as a new source of collagen for industrial purposes.展开更多
Pepsin was assembled on the surface of prepared poly(ethylene terephthalate)(PET-NH3^+) substrates.The composition and structure of the pepsin/PET-NH3^+ assembling films in different condition were characterized by X-...Pepsin was assembled on the surface of prepared poly(ethylene terephthalate)(PET-NH3^+) substrates.The composition and structure of the pepsin/PET-NH3^+ assembling films in different condition were characterized by X-ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFM).展开更多
Characteristics and antioxidant activities of pepsin-soluble collagen （PSC） from yellow goosefish （Lophius litulon） skins were investigated. PSC was characterized as a type I collagen, and its imino acid content w...Characteristics and antioxidant activities of pepsin-soluble collagen （PSC） from yellow goosefish （Lophius litulon） skins were investigated. PSC was characterized as a type I collagen, and its imino acid content was 193 residues/1 000 residues. PSC＇s denaturation temperature was -17.56℃ and Fourier transform infrared spectra confirmed the presence of triple helices. Solubility analysis showed good solubility at acidic pH （1-6） or low NaCl concentrations （≤2%）. PSC showed scavenging activity against hydroxyl radicals and superoxide anions in a concentration-dependent manner. Furthermore, PSC could protect D-galactose-induced skin aging by significantly controlling malondialdehyde formation and improving the activity of superoxide dismutase, glutathione peroxidase, catalase, glutathione, and hydroxyproline. PSC may be a promising antioxidant in appropriate applications.展开更多
The aim of this study was to compare chemical and biochemical properties of crude jellyfish protein extracted from salted sand jellyfish （Rhopilema hispidum） and white jellyfish （Lobonema smithii）. Sodium dodecyl ...The aim of this study was to compare chemical and biochemical properties of crude jellyfish protein extracted from salted sand jellyfish （Rhopilema hispidum） and white jellyfish （Lobonema smithii）. Sodium dodecyl sulfate polyacylamide gel electrophoresis （SDS-PAGE） showed that the principal proteins of collagen standard types I and II were found among the protein constituents of desalted jellyfish collagen prepared in this study. The amino acid compositions of extracted collagen were typical collagen. The denaturation temperature （Td） of extracted collagen samples was 28-29 ℃. The solubility of all extracted collagens was found up to 4% NaCl. The results indicated that the commercial salting process could partially denature native jellyfish protein functionalities. However, the collagen could be extracted from desalted jellyfish for future use as a food ingredient.展开更多
The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. Acco...The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. According to the results, adsorption capacity and catalytic activity of enzymes depend on the physical nature of surface groups of the solid phase. Changing the stability of enzymes in the system with solid phase is observed even the adsorption bond is less stable （in the case of DEAE- and CM-cellulose in acidic media）. Injection to the medium ethanol, surfactants, sodium chloride and changing the temperature of the incubation medium could prevent the negative effects of the solid phases. When sorsilen is used as solid phase, pepsin and acidic protease from Asp. awamori suffer from high surface inactivation. Various surfactants influence adsorption state of enzymes differently. Non-ionic surfactants （Triton X-100） prevent adsorption and restore catalytic properties of enzymes.展开更多
Background:Gastroesophageal reflux disease(GERD)is heterogeneous with a varied symptom spectrum and reflux profiles.Its definite diagnosis often requires invasive tools including endoscopy or reflux monitoring.The aim...Background:Gastroesophageal reflux disease(GERD)is heterogeneous with a varied symptom spectrum and reflux profiles.Its definite diagnosis often requires invasive tools including endoscopy or reflux monitoring.The aim of this study was to investigate the clinical relevance of salivary pepsin detection as a non-invasive screening tool to diagnose GERD of different subtypes.Methods:A total of 77 patients with suspected GERD symptoms and 12 asymptomatic controls were analysed.All participants performed symptom evaluation,upper endoscopy,esophageal manometry,and 24-hour multichannel intraluminal impedance-dual pH probe monitoring.Saliva was self-collected across three different time points:at early fasting,postprandially,and at symptom occurrence.Salivary pepsin levels were measured via Peptest.The optimal threshold of salivary pepsin for diagnosing distal or proximal reflux was determined according to a receiver-operating characteristic curve.Results:The average salivary pepsin concentration of suspected GERD patients was significantly higher than that of controls(100.63[68.46,141.38]vs 67.90[31.60,115.06]ng/mL,P=0.044),although no difference was found among patients with different symptom spectrums.The distal reflux group had a higher average pepsin concentration than non-reflux patients(170.54[106.31,262.76]vs 91.13[63.35,127.63]ng/mL,P=0.043),while no difference was observed between the distal reflux group and the proximal reflux group.The optimal cut-off value of salivary pepsin concentration for diagnosing pathological distal reflux was 157.10 ng/mL,which was higher than that for diagnosing pathological proximal reflux(122.65 ng/mL).The salivary pepsin concentration was significantly correlated with distal and proximal reflux parameters.Conclusions:Salivary pepsin measurement can help in identifying true GERD with pathological distal reflux or proximal reflux,regardless of different symptom spectrums.A higher threshold should be applied for diagnosing distal reflux than for proximal reflux.展开更多
基金supported by the National Natural Science Foundation of China(21808020)the Applied Basic Research Program of Science&Technology Department of Sichuan Province(2018JY0151)。
文摘Phlorizin(PHL)is a natural compound with strong antioxidant properties mainly found in apples.In this paper,the interaction mechanism of PHL with pepsin and trypsin was comparatively evaluated by computer simulation,fluorescence spectra,circular dichroism(CD),and Fourier transform infrared(FT-IR)spectra at a molecular level.Fluorescence spectra showed that PHL quenches the pepsin/trypsin by static quenching.Thermodynamic parameters indicated that PHL binds to pepsin mainly through hydrogen bonds and van der Waals forces,and that of trypsin was electrostatic forces.The ground state complexes PHL and protease have a moderate affinity of 105 L/mol PHL binds more strongly to trypsin than to pepsin.CD and FT-IR spectra results showed that pepsin/trypsin decreased theβ-sheet content and slightly changed its secondary structure upon PHL.These experimental results are mutually verified with the predicted computer-aid simulation results.Upon PHL and trypsin binding,the antioxidant capacity of PHL was elevated.Nevertheless,the antioxidant capacity of PHL was decreased after binding to pepsin.This work elucidates the binding of PHL binding mechanisms to pepsin/trypsin and provides useful information for the digestion of PHL to improve the application of PHL in food processing.
基金This work was financially assisted by the Natural Science Foundation of Guangdong Province(2021A1515010615,2022A1515012520)Special Fund for Science and Technology Innovation Strategy of Guangdong Province(2021S0052,2022DZXHT015,2023S003040,2023S002024,2022S035)Projects of Talents Recruitment of GDUPT(519030).
文摘Hispidin is a pyranone compound found in edible and medicinal mushrooms of the Phellinus and Inonotus genera.This investigation used fluorescence spectroscopy,UV absorption spectroscopy,and molecular docking to examine the interaction of hispidin with pepsin.The Stern-Volmer method was used to perform the fluorescence quenching measurements at different temperatures(298 K,303 K,and 310 K).According to the findings,hispidin induced a static quenching mechanism in pepsin that resulted in the creation of a hispidin-pepsin complex with binding constants(Ka)ranging from 9.56×10^(4) to 3.45×10^(5) L mol^(-1).The positive values ofΔH(84.6 kJ mol-1)andΔS(337.9 J mol^(-1) K^(-1))demonstrated that hydrophobic forces contributed to forming the hispidin-pepsin complex.The findings of UV-vis absorption,synchronous fluorescence,and 3D fluorescence spectraspectra demonstrated that hispidin altered the conformation and microenvironment of pepsin.According to the analysis of molecular docking,hispidin got into the pepsin's active cavity.The research clarifies the molecular mechanisms by which hispidin binds to pepsin and helps understand its possible biological activity in vivo.
基金Funded by the National Natural Science Foundation of China(No.51173143)
文摘By using the wastes fish skin of sturgeon processed as a raw material, a macromolecule biomaterial of collagen was extracted. Acid-soluble collagen(ASC) and pepsin-soluble collagen(PSC) were successfully isolated from the skin of hybrid sturgeon with two extraction methods. The yields of ASC and PSC based on the wet weight of skin were 5.73 ± 0.11% and 10.26 ± 0.39%, respectively. The denaturation and melting points of ASC(26.83 ℃ and 110.49 ℃) and PSC(26.54 ℃ and 102.99 ℃) were assessed by Circular dichroism(CD) and Differential scanning calorimetry(DSC). ASC and PSC appeared to be dense sheet-like film linked by random-coiled filaments under scanning electron microscopy(SEM). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Fourier transform infrared spectroscopy(FTIR) confirmed that both the ASC and PSC were Type I collagen and maintained a complete triple helix structure. These results indicated that both ASC and PSC possessed good biological activity and could be widely used in medical biomaterials and other fields.
文摘The pepsin and trypsin activities and some of the properties of the two enzymes of southern sheatfish larvae were studied. The results were as follows: the highest level of trypsin activity is in the foregut in all measured tissues; from foregut to hindgut, trypsin activities decrease; the pH optimum of trypsin activity is pH9.0; the strongest pepsin activity is in the stomach; the proper density of haemoglobin for detecting pepsin activity is 1.0%. These data are useful in solving applied nutritional problems, such as the adequacy of artificial food to the digestive abilities of the fish.
文摘To make more effective use of underutilized resources, pepsin-solubilized collagen (PSC) was successfully extracted from the skin of black carp (Mylopharyngdon piceus) with a yield of 45.7% based on dry weight. The PSC comprising two identical α1-chains and one α2-chain with no disulfide bond was characterized as type I, and it contained 195 imino acid residues vs. 1000 amino acid residues. The collagen showed an absorption edge around 218 nm, which was lower than the maximum absorption wavelength of other PSC. The denaturation temperature of PSC was 25.6°C, which was lower than that of porcine collagen by approximately 11°C. The isoelectric point (pI) was estimated to be 8.23, and the collagen was soluble at an acidic pH as well as below 40 g/L NaCl. It is thought that the high yield and stability of PSC from the skin of black carp warrant its application as a new source of collagen for industrial purposes.
文摘Pepsin was assembled on the surface of prepared poly(ethylene terephthalate)(PET-NH3^+) substrates.The composition and structure of the pepsin/PET-NH3^+ assembling films in different condition were characterized by X-ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFM).
基金Supported by the International S&T Cooperation Program of China(No.2015DFA30980)the Zhejiang Provincial Natural Science Foundation of China(No.LQ14C170001)the Special Program for the Science and Technology Plan of Zhejiang Province(No.2011C02003)
文摘Characteristics and antioxidant activities of pepsin-soluble collagen （PSC） from yellow goosefish （Lophius litulon） skins were investigated. PSC was characterized as a type I collagen, and its imino acid content was 193 residues/1 000 residues. PSC＇s denaturation temperature was -17.56℃ and Fourier transform infrared spectra confirmed the presence of triple helices. Solubility analysis showed good solubility at acidic pH （1-6） or low NaCl concentrations （≤2%）. PSC showed scavenging activity against hydroxyl radicals and superoxide anions in a concentration-dependent manner. Furthermore, PSC could protect D-galactose-induced skin aging by significantly controlling malondialdehyde formation and improving the activity of superoxide dismutase, glutathione peroxidase, catalase, glutathione, and hydroxyproline. PSC may be a promising antioxidant in appropriate applications.
文摘The aim of this study was to compare chemical and biochemical properties of crude jellyfish protein extracted from salted sand jellyfish （Rhopilema hispidum） and white jellyfish （Lobonema smithii）. Sodium dodecyl sulfate polyacylamide gel electrophoresis （SDS-PAGE） showed that the principal proteins of collagen standard types I and II were found among the protein constituents of desalted jellyfish collagen prepared in this study. The amino acid compositions of extracted collagen were typical collagen. The denaturation temperature （Td） of extracted collagen samples was 28-29 ℃. The solubility of all extracted collagens was found up to 4% NaCl. The results indicated that the commercial salting process could partially denature native jellyfish protein functionalities. However, the collagen could be extracted from desalted jellyfish for future use as a food ingredient.
文摘The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. According to the results, adsorption capacity and catalytic activity of enzymes depend on the physical nature of surface groups of the solid phase. Changing the stability of enzymes in the system with solid phase is observed even the adsorption bond is less stable （in the case of DEAE- and CM-cellulose in acidic media）. Injection to the medium ethanol, surfactants, sodium chloride and changing the temperature of the incubation medium could prevent the negative effects of the solid phases. When sorsilen is used as solid phase, pepsin and acidic protease from Asp. awamori suffer from high surface inactivation. Various surfactants influence adsorption state of enzymes differently. Non-ionic surfactants （Triton X-100） prevent adsorption and restore catalytic properties of enzymes.
基金supported by the Guangdong Natural Science Foundation[grant number 2023A1515010187]the Guangdong provincial and municipal Joint Fund[grant number 2022A1515111159]the China National Natural Science Foundation[grant numbers 82170577 and 81970479].
文摘Background:Gastroesophageal reflux disease(GERD)is heterogeneous with a varied symptom spectrum and reflux profiles.Its definite diagnosis often requires invasive tools including endoscopy or reflux monitoring.The aim of this study was to investigate the clinical relevance of salivary pepsin detection as a non-invasive screening tool to diagnose GERD of different subtypes.Methods:A total of 77 patients with suspected GERD symptoms and 12 asymptomatic controls were analysed.All participants performed symptom evaluation,upper endoscopy,esophageal manometry,and 24-hour multichannel intraluminal impedance-dual pH probe monitoring.Saliva was self-collected across three different time points:at early fasting,postprandially,and at symptom occurrence.Salivary pepsin levels were measured via Peptest.The optimal threshold of salivary pepsin for diagnosing distal or proximal reflux was determined according to a receiver-operating characteristic curve.Results:The average salivary pepsin concentration of suspected GERD patients was significantly higher than that of controls(100.63[68.46,141.38]vs 67.90[31.60,115.06]ng/mL,P=0.044),although no difference was found among patients with different symptom spectrums.The distal reflux group had a higher average pepsin concentration than non-reflux patients(170.54[106.31,262.76]vs 91.13[63.35,127.63]ng/mL,P=0.043),while no difference was observed between the distal reflux group and the proximal reflux group.The optimal cut-off value of salivary pepsin concentration for diagnosing pathological distal reflux was 157.10 ng/mL,which was higher than that for diagnosing pathological proximal reflux(122.65 ng/mL).The salivary pepsin concentration was significantly correlated with distal and proximal reflux parameters.Conclusions:Salivary pepsin measurement can help in identifying true GERD with pathological distal reflux or proximal reflux,regardless of different symptom spectrums.A higher threshold should be applied for diagnosing distal reflux than for proximal reflux.
