Objective:To analyze the amino acid sequence composition,secondary structure,the spatial conformation of its domain and other characteristics of Argonaute protein.Methods:Bioinformatics tools and the internet server w...Objective:To analyze the amino acid sequence composition,secondary structure,the spatial conformation of its domain and other characteristics of Argonaute protein.Methods:Bioinformatics tools and the internet server were used.Firstly,the amino acid sequence composition features of the Argonaute protein were analyzed,and the phylogenetic tree was constructed.Secondly,Argonaute protein's distribution of secondary structure and its physicochemical properties were predicted.Lastly,the protein functional expression form of the domain group was established through the Phyre-based analysis on the spatial conformation of Argonaute protein domains.Results:593 amino acids were encoded by Argonaute protein,the phylogenetic tree was constructed,and Argonaute protein's distribution of secondary structure and its physicochemical properties were obtained through analysis.In addition,the functional expression form which comprised the N-terminal PAZ domain and C-terminal Piwi domain for the Argonaute protein was obtained with Phyre.Conclusions:The information relationship between the structure and function of the Argonaute protein can be initially established with bioinformatics tools and the internet server,and this provides the theoretical basis for further clarifying the function of Schistosoma Argonaute protein.展开更多
Understanding material-protein interactions is the basis for regulating material-blood interactions,which is a common topic of interest for medical material developers.In recent years,researchers have conducted extens...Understanding material-protein interactions is the basis for regulating material-blood interactions,which is a common topic of interest for medical material developers.In recent years,researchers have conducted extensive studies on(1)the structural charac-teristics of the plasma protein adsorption layer on the material surface,including the evolution of the protein adsorption layer and its typical binary structure.(2)Influence factors of the protein adsorption layer formation include protein factors(e.g.,isoelectric point,structural stability),material factors(e.g.,wettability,surface charge,morphology,size),and environmental factors.(3)Effects of some common plasma proteins in the protein adsorption layer on material-blood interactions.Here,we review the important research results in this field,hoping to provide a reference for future development of advanced blood contact materials.展开更多
Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated...Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored substrates.The mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force microscopy.The mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon resonance.When the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,respectively.It is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than the pK_(a) of PDMAEMA)exhibited slight展开更多
The conformations of bovine serum albumin (USA) and egg albumin (EA) in solution and their conformation changes under different conditions were studied by using three-dimensional fluorescence spectrometry (TDFS) such ...The conformations of bovine serum albumin (USA) and egg albumin (EA) in solution and their conformation changes under different conditions were studied by using three-dimensional fluorescence spectrometry (TDFS) such as three-dimensional fluorescence (TDF) spectra and three-dimensional fluorescence polarization (TDFP) spectra with tryptophan residues in protein molecules as an intrinsic fluorescent probe. The results show that the microenvironment of tryptophan residues of protein molecules in various solutions can be directly indicated and TDFS is an effective tool for studying protein conformation in solution. Meantime, some valuable results were obtained.展开更多
With increased demand for plant based proteins by the consumers, the food manufacturers appeal for the new plant proteins with predetermined characteristics. This study aims at isolating the protein fraction from jack...With increased demand for plant based proteins by the consumers, the food manufacturers appeal for the new plant proteins with predetermined characteristics. This study aims at isolating the protein fraction from jackfruit seeds and characterizing the protein powder for functional and physicochemical properties. The protein part of the seeds was separated through pH treatments and centrifugation process and finally, the concentrate was converted into powder by spray drying method. The functional properties such as solubility, gelling capacity and emulsion properties and the physicochemical properties such as crystallinity, morphology and particle size distribution of the jackfruit seeds protein isolate (JSPI) were studied. The secondary structural elements of JSPI were also determined by Fourier-transform infrared (FTIR) spectroscopy. About 76.89% protein was estimated in the prepared JSPI with 78.44% solubility in an aquatic solvent. The least gelation concentration of JSPI was 12% in a salt solution. The pH of the solvent significantly affected the emulsifying and foaming properties. The protein isolate possessed amorphous structure, moderate bulk density and almost 75% of the particles fell in a similar size distribution range. The conformational study reported that the β-sheet is the dominant secondary structural element with the highest content of 50.28%. The observed features suggest that the JSPI holds satisfactory functional and physicochemical characteristics for being used in protein-enriched foods.展开更多
The surface pressure-area (π-A) isotherm of R-phycoerythrin (R-PE) at the air-water interface has been measured. The results indicate that R-PE can form the monomolecular film. Moreover, the molecule-occupied area ex...The surface pressure-area (π-A) isotherm of R-phycoerythrin (R-PE) at the air-water interface has been measured. The results indicate that R-PE can form the monomolecular film. Moreover, the molecule-occupied area extrapolating the linear part of the n-A isotherm is identical with that when an R-PE molecule is located at the interface with its disk plane parallel to the air-water interface. The transmission electron micrograph (TEM) and the measurement of the thickness of the protein monolayer by ellipsometry show that the orientation of R-PE disk plane on the substrate is parallel to the plane of substrate. Absorption and fluorescence spectra of R-PE LB multilayers were obtained through transferring R-PE monolayer at the air-water interface to the substrates at the proper surface pressure by Langmuir-Blodgett (LB) technique. These spectra of R-PE LB films do not show distinct differences from those in aqueous solution. Comparative studies of circular dichroism (CD) spectra of the protein between in aqueous solution and in LB film show that the changes of the secondary structure of R-PE take place, i.e. the β-sheet component of the protein increases in the LB films.展开更多
Molecular weights of the silk fibroin were determined by polyacrylamide gel electrophoresis in the presence of so-didium dodecyl sulfate (SDS - PAGE): The silk fibroin molecule consisted of subunits a, b and c with mo...Molecular weights of the silk fibroin were determined by polyacrylamide gel electrophoresis in the presence of so-didium dodecyl sulfate (SDS - PAGE): The silk fibroin molecule consisted of subunits a, b and c with molecular weights of 280 kD, 230 kD and 25 kD respectively, of which the b subunit was composed of two subunits e and f with molecular weights of 130 kD and 125 kD, respec-tively, connected by disulfide bonds. The conformation of silk fibroin and subunits was determinated by Raman spectroscopy and Large angle X - ray diffraction) LAXS. The native silk fibroin only contained a - helix and random coil, but there were three conformation such as random - coil.a - helix and β - sheet in the silk fibroin dissolved in KSCN solution and frozen at - 20 °C. This suggested that KSCN solution and - 20°C freezing action could lead to the conformational transi-tion from random - coil and a - helix to P - sheet. The a subunit mainly existed in β - sheet conformation, in con-trast, the c subunit was展开更多
The cross-linked crystals of Concanavalin A were soaked in water and in anhydrous acetonitrile as well as were re-soaked in water after soaking in acetonitrile. Their structures were determined by X-ray crystallograph...The cross-linked crystals of Concanavalin A were soaked in water and in anhydrous acetonitrile as well as were re-soaked in water after soaking in acetonitrile. Their structures were determined by X-ray crystallography and compared with the uncross-linked native structure. One of them, which was soaked in net acetonitrile, underwent considerable changes in the diffraction pattern when soaked in net acetonitrile. Its cell parameters are 0.45 and 0. 57 nm shorter ina axis and inb axis, but 0.12 nm longer inc axis than those of the native, respectively. It was found that acetonitrile has an effect on the conformation of poly peptide chain in the flexible turn and loop regions, except for β-sheets. The confornation of cross-linked structure in soaked acetonitrile may recorvered to the native when re-soaked in water, and its conserved acetonitrile molecule is used as a probe to exploit the regions of protein surface with specificity and affinity.展开更多
Although the native state and the fully unfolded state of proteins have been extensively studied, the folding pathway and intermediates in the protein folding process have not been thoroughly investigated. To understa...Although the native state and the fully unfolded state of proteins have been extensively studied, the folding pathway and intermediates in the protein folding process have not been thoroughly investigated. To understand the mechanisms of protein folding, the early intermediates in the protein folding process must be clearly characterized. The present paper is a mini review containing 20 references involving studies on folding intermediates of several proteins. 展开更多
Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fat...Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fatty acids are essential. Life style in Western civilization leads to deprivation of essential fatty acids, to elevated serum-cholesterol-levels and to autoimmunity. Here the hypothesis is presented, and explains the relationship: deprivation of essential fatty acids lead to imminent quasi-crystallization of the membrane. Serum cholesterol-levels are elevated. Incorporation of cholesterol into membranes enhancing fluidity again, is able to repair the effect. At saturation, repair fails. Quasi-crystallization occurs. Proteins tilt into another conformation. This has not been learned during the “self” recognition process of the immune system during the embryonic phase. Immune system attacks the new conformation as “non-self”, autoimmunity emerges.展开更多
基金Supported by the the natural sciences plan projects of educationdepartment of Henan province(No:2010A310018)
文摘Objective:To analyze the amino acid sequence composition,secondary structure,the spatial conformation of its domain and other characteristics of Argonaute protein.Methods:Bioinformatics tools and the internet server were used.Firstly,the amino acid sequence composition features of the Argonaute protein were analyzed,and the phylogenetic tree was constructed.Secondly,Argonaute protein's distribution of secondary structure and its physicochemical properties were predicted.Lastly,the protein functional expression form of the domain group was established through the Phyre-based analysis on the spatial conformation of Argonaute protein domains.Results:593 amino acids were encoded by Argonaute protein,the phylogenetic tree was constructed,and Argonaute protein's distribution of secondary structure and its physicochemical properties were obtained through analysis.In addition,the functional expression form which comprised the N-terminal PAZ domain and C-terminal Piwi domain for the Argonaute protein was obtained with Phyre.Conclusions:The information relationship between the structure and function of the Argonaute protein can be initially established with bioinformatics tools and the internet server,and this provides the theoretical basis for further clarifying the function of Schistosoma Argonaute protein.
基金National Natural Science Foundation of China,Grant/Award Numbers:31570957,21875092National Key Research and Development Program of China,Grant/Award Numbers:2019YFA0112000,2017YFB0702504。
文摘Understanding material-protein interactions is the basis for regulating material-blood interactions,which is a common topic of interest for medical material developers.In recent years,researchers have conducted extensive studies on(1)the structural charac-teristics of the plasma protein adsorption layer on the material surface,including the evolution of the protein adsorption layer and its typical binary structure.(2)Influence factors of the protein adsorption layer formation include protein factors(e.g.,isoelectric point,structural stability),material factors(e.g.,wettability,surface charge,morphology,size),and environmental factors.(3)Effects of some common plasma proteins in the protein adsorption layer on material-blood interactions.Here,we review the important research results in this field,hoping to provide a reference for future development of advanced blood contact materials.
基金the financial support of the National Natural Science Foundation of China(21674102)。
文摘Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored substrates.The mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force microscopy.The mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon resonance.When the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,respectively.It is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than the pK_(a) of PDMAEMA)exhibited slight
基金Project supported by the National Natural Science Foundation of China
文摘The conformations of bovine serum albumin (USA) and egg albumin (EA) in solution and their conformation changes under different conditions were studied by using three-dimensional fluorescence spectrometry (TDFS) such as three-dimensional fluorescence (TDF) spectra and three-dimensional fluorescence polarization (TDFP) spectra with tryptophan residues in protein molecules as an intrinsic fluorescent probe. The results show that the microenvironment of tryptophan residues of protein molecules in various solutions can be directly indicated and TDFS is an effective tool for studying protein conformation in solution. Meantime, some valuable results were obtained.
文摘With increased demand for plant based proteins by the consumers, the food manufacturers appeal for the new plant proteins with predetermined characteristics. This study aims at isolating the protein fraction from jackfruit seeds and characterizing the protein powder for functional and physicochemical properties. The protein part of the seeds was separated through pH treatments and centrifugation process and finally, the concentrate was converted into powder by spray drying method. The functional properties such as solubility, gelling capacity and emulsion properties and the physicochemical properties such as crystallinity, morphology and particle size distribution of the jackfruit seeds protein isolate (JSPI) were studied. The secondary structural elements of JSPI were also determined by Fourier-transform infrared (FTIR) spectroscopy. About 76.89% protein was estimated in the prepared JSPI with 78.44% solubility in an aquatic solvent. The least gelation concentration of JSPI was 12% in a salt solution. The pH of the solvent significantly affected the emulsifying and foaming properties. The protein isolate possessed amorphous structure, moderate bulk density and almost 75% of the particles fell in a similar size distribution range. The conformational study reported that the β-sheet is the dominant secondary structural element with the highest content of 50.28%. The observed features suggest that the JSPI holds satisfactory functional and physicochemical characteristics for being used in protein-enriched foods.
基金Project supported by the National Natural Science Foundation of China
文摘The surface pressure-area (π-A) isotherm of R-phycoerythrin (R-PE) at the air-water interface has been measured. The results indicate that R-PE can form the monomolecular film. Moreover, the molecule-occupied area extrapolating the linear part of the n-A isotherm is identical with that when an R-PE molecule is located at the interface with its disk plane parallel to the air-water interface. The transmission electron micrograph (TEM) and the measurement of the thickness of the protein monolayer by ellipsometry show that the orientation of R-PE disk plane on the substrate is parallel to the plane of substrate. Absorption and fluorescence spectra of R-PE LB multilayers were obtained through transferring R-PE monolayer at the air-water interface to the substrates at the proper surface pressure by Langmuir-Blodgett (LB) technique. These spectra of R-PE LB films do not show distinct differences from those in aqueous solution. Comparative studies of circular dichroism (CD) spectra of the protein between in aqueous solution and in LB film show that the changes of the secondary structure of R-PE take place, i.e. the β-sheet component of the protein increases in the LB films.
基金the Foundation of Hao Yingdong Youth Teacher and Shanghai Youth Scientific
文摘Molecular weights of the silk fibroin were determined by polyacrylamide gel electrophoresis in the presence of so-didium dodecyl sulfate (SDS - PAGE): The silk fibroin molecule consisted of subunits a, b and c with molecular weights of 280 kD, 230 kD and 25 kD respectively, of which the b subunit was composed of two subunits e and f with molecular weights of 130 kD and 125 kD, respec-tively, connected by disulfide bonds. The conformation of silk fibroin and subunits was determinated by Raman spectroscopy and Large angle X - ray diffraction) LAXS. The native silk fibroin only contained a - helix and random coil, but there were three conformation such as random - coil.a - helix and β - sheet in the silk fibroin dissolved in KSCN solution and frozen at - 20 °C. This suggested that KSCN solution and - 20°C freezing action could lead to the conformational transi-tion from random - coil and a - helix to P - sheet. The a subunit mainly existed in β - sheet conformation, in con-trast, the c subunit was
文摘The cross-linked crystals of Concanavalin A were soaked in water and in anhydrous acetonitrile as well as were re-soaked in water after soaking in acetonitrile. Their structures were determined by X-ray crystallography and compared with the uncross-linked native structure. One of them, which was soaked in net acetonitrile, underwent considerable changes in the diffraction pattern when soaked in net acetonitrile. Its cell parameters are 0.45 and 0. 57 nm shorter ina axis and inb axis, but 0.12 nm longer inc axis than those of the native, respectively. It was found that acetonitrile has an effect on the conformation of poly peptide chain in the flexible turn and loop regions, except for β-sheets. The confornation of cross-linked structure in soaked acetonitrile may recorvered to the native when re-soaked in water, and its conserved acetonitrile molecule is used as a probe to exploit the regions of protein surface with specificity and affinity.
文摘Although the native state and the fully unfolded state of proteins have been extensively studied, the folding pathway and intermediates in the protein folding process have not been thoroughly investigated. To understand the mechanisms of protein folding, the early intermediates in the protein folding process must be clearly characterized. The present paper is a mini review containing 20 references involving studies on folding intermediates of several proteins.
文摘Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fatty acids are essential. Life style in Western civilization leads to deprivation of essential fatty acids, to elevated serum-cholesterol-levels and to autoimmunity. Here the hypothesis is presented, and explains the relationship: deprivation of essential fatty acids lead to imminent quasi-crystallization of the membrane. Serum cholesterol-levels are elevated. Incorporation of cholesterol into membranes enhancing fluidity again, is able to repair the effect. At saturation, repair fails. Quasi-crystallization occurs. Proteins tilt into another conformation. This has not been learned during the “self” recognition process of the immune system during the embryonic phase. Immune system attacks the new conformation as “non-self”, autoimmunity emerges.
