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Xiuzhi Susan Sun - One of the best experts on this subject based on the ideXlab platform.
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Physico-chemical properties of camelina protein altered by sodium bisulfite and guanidine-HCl
Industrial Crops and Products, 2016Co-Authors: Xiangwei Zhu, Xiuzhi Susan SunAbstract:The objective of this research was to investigate the unfolding behaviors of camelina protein isolate (CPI) induced by sodium bisulfite (NaHSO3) and guanidine–HCl (Gdm.Cl). Protein was extracted from defatted camelina meal through alkali solubilization and acid precipitation and modified with varying amount of NaHSO3(0–12% of the protein dry basis) and Gdm.Cl (0–250% of the protein, dry basis). NaHSO3treatment broke the disulfide bonds of the CPI and increased free sulfhydryl content and surface hydrophobicity. As NaHSO3concentration increased, the viscosity, elastic modulus (G’) and water resistant of NaHSO3-modified camelina protein (SMCP) dispersion decreased, and the protein became aggregated due to high surface hydrophobicity. Gdm.Cl treatment broke the CPI's hydrogen bonds but decreased their surface hydrophobicity. Similarly, viscosity, G’, and water resistant of Gdm.Cl-modified camelina protein (GMCP) dispersions decreased as Gdm.Cl increased and protein aggregation formed. The reducing effect of NaHSO3was greater than Gdm.Cl for CPI's protein–protein interaction and less obvious for the viscosity and water resistant. Gdm.Cl reduced CPI's decomposing temperature at high concentration, but no remarkable effect was observed for NaHSO3treatment. These findings on physicochemical changes of SMCPs and GMCPs may contribute to the application of camelina proteins in the biodegradable materials products.
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Sodium Bisulfite-Induced Changes in the Physicochemical, Surface and Adhesive Properties of Soy β-Conglycinin
Journal of the American Oil Chemists' Society, 2010Co-Authors: Xiuzhi Susan SunAbstract:The effects of sodium bisulfite on the electrophoresis profile; turbidity; and thermal, surface, and adhesive properties of soy β-conglycinin protein were studied. Sodium bisulfite dissociated high-molecular-weight aggregates in the protein, and the aggregate percentage decreased with increasing sodium bisulfite concentration. Denaturation temperature of sodium-bisulfite-treated β-conglycinin increased as sodium bisulfite increased. However, at high sodium bisulfite concentration (i.e. 36 g/L), denaturation enthalpy decreased significantly. Sodium bisulfite caused changes in the β-conglycinin secondary structure and promoted ionization of lysine residues as indicated by FT-IR results. A sudden drop in turbidity at pH 4.8 was observed at the same salt level. The contact angle of β-conglycinin on cherry wood reached its minimum at 6 g/L sodium bisulfite and 24 g/L on glass. Water resistance of β-conglycinin was improved but not significantly by 6 g/L sodium bisulfite at pH 9.5. An obvious increase in adhesion strength of the protein occurred at 3 and 6 g/L sodium bisulfite at pH 4.8. A high sodium bisulfite concentration at 36 g/L sharply reduced the adhesive performance of β-conglycinin.
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Effect of sodium bisulfite on properties of soybean glycinin
Journal of Agricultural and Food Chemistry, 2008Co-Authors: Xiuzhi Susan SunAbstract:The objective of this work is to understand the function of glycinin in soy protein adhesive formation. Glycinin protein was treated with sodium bisulfite, and physicochemical, morphological, and adhesion properties of the modified soy glycinin were characterized. More disulfide bonds that associated acidic and basic polypeptides of glycinin broke as the sodium bisulfite concentration increased. The reduction of disulfide bonds did not decrease the thermal stability of glycinin. Instead, the denaturation temperature of modified glycinin increased as sodium bisulfite increased. Sodium bisulfite-induced disulfide bond cleavage increased the surface hydrophobicity of modified glycinin. Hydrophobic force is the main driving force for glycinin aggregation, and the balance between hydrophobic and electrostatic forces makes glycinin form chainlike aggregates. The adhesive strength and water resistance of glycinin dropped significantly at lower levels of sodium bisulfite and then increased as the amount of sodium bisulfite increased up to 24 g/L. The adhesive performance decreased again with further addition of sodium bisulfite. The adhesive strength of glycinin was not improved by sodium bisulfite modification in the studied range.
P Rio - One of the best experts on this subject based on the ideXlab platform.
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synthesis of cationic flocculants by the inverse microemulsion copolymerization of acrylamide with 60 2 acryloxyethyltrimethyl ammonium chloride in the monomer feed i initiation by ammonium persulfate sodium Disulfite redox system
Journal of Applied Polymer Science, 2007Co-Authors: F Escudero J Sanz, J Ochoa R Gomez, Pedro M Sasia, Diaz E De Apodaca, P RioAbstract:Acrylamide/2-acryloxyethyltrimethyl ammon-ium chloride copolymers in inverse microemulsion, with a cationic charge density of 60% and a concentration of active matter of 30 wt %, of interest as flocculants have been obtained by inverse microemulsion copolymerization. Interesting inverse microemulsion formulations from both industrial and economical standpoints were selected from pseudoternary phase diagrams. These formulations were polymerized by semicontinuous free radical copolymerization in inverse microemulsion using sodium Disulfite and ammonium persulfate as initiators. Influence of initiators and initiator addition conditions (specific flow rate and concentration) on semicontinuous polymerization and final product properties as flocculants have been studied. A strong difference in copolymer solution viscosity has been found when an aqueous solution of sodium Disulfite is used as initiator instead of sodium Disulfite/ammonium persulfate couple redox, specially for low sodium Disulfite solution feeding flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2826–2836, 2007
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Synthesis of cationic flocculants by the inverse microemulsion copolymerization of acrylamide with 60% 2‐acryloxyethyltrimethyl ammonium chloride in the monomer feed. I. Initiation by ammonium persulfate/sodium Disulfite redox system
Journal of Applied Polymer Science, 2006Co-Authors: F. J. Escudero Sanz, Pedro M Sasia, J. R. Ochoa Gómez, E. Díaz De Apodaca, P RioAbstract:Acrylamide/2-acryloxyethyltrimethyl ammon-ium chloride copolymers in inverse microemulsion, with a cationic charge density of 60% and a concentration of active matter of 30 wt %, of interest as flocculants have been obtained by inverse microemulsion copolymerization. Interesting inverse microemulsion formulations from both industrial and economical standpoints were selected from pseudoternary phase diagrams. These formulations were polymerized by semicontinuous free radical copolymerization in inverse microemulsion using sodium Disulfite and ammonium persulfate as initiators. Influence of initiators and initiator addition conditions (specific flow rate and concentration) on semicontinuous polymerization and final product properties as flocculants have been studied. A strong difference in copolymer solution viscosity has been found when an aqueous solution of sodium Disulfite is used as initiator instead of sodium Disulfite/ammonium persulfate couple redox, specially for low sodium Disulfite solution feeding flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2826–2836, 2007
Akinori Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Assignment of disulfide bond location in prothoracicotropic hormone of the silkworm, Bombyx mori: a homodimeric peptide.
Biochemistry, 1994Co-Authors: Jun Ishibashi, Hiroshi Kataoka, Akira Isogai, Atsushi Kawakami, Hironao Saegusa, Yoshimasa Yagi, Akira Mizoguchi, Hironori Ishizaki, Akinori SuzukiAbstract:The disulfide bond location of a homodimeric peptide, prothoracicotropic hormone (PTTH) of the silkworm, Bombyx mori, was determined by a combination of partial reduction and sequence analysis of peptide fragments generated through a partial reduction of PTTH followed by alkylation and enzyme digestion. The partial reduction and S-alkylation broke the interchain disulfide bond but did not affect the intrachain disulfide bonds, generating monomeric PTTH whose intrachain disulfide bonds were kept intact. This monomeric PTTH has about one-half the biological activity of intact PTTH. Sequence analysis of the fragments generated by lysyl endopeptidase digestion of this monomeric PTTH after complete reduction and S-alkylation by another S-alkylating reagent showed that only the Cys15 residue was reduced and S-alkylated by the foregoing partial reduction, indicating that this residue formed the interchain disulfide bond. The other disulfide bonds which formed intrachain bridgings were determined by sequence and mass analyses of the fragments generated by two successive enzyme digestions of the monomeric PTTH. In conclusion, the disulfide bond location of PTTH was assigned to Cys15-Cys15' as an interchain disulfide linkage and Cys17-Cys54, Cys40-Cys96, and Cys48-Cys98 as intrachain disulfide linkages.
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Bombyxin-II and its disulfide bond isomers: synthesis and activity.
Peptides, 1992Co-Authors: Koji Nagata, Akira Isogai, Hironori Ishizaki, Kazunori Maruyama, Hiromichi Nagasawa, Ikumi Urushibata, Akinori SuzukiAbstract:Abstract Bombyxin-II, an insulin superfamily peptide of the silkmoth Bombyx mori, and its disulfide bond isomers have been synthesized by two ways of stepwise, semiregioselective disulfide bond formation. The disulfide bond CysA20-CysB22 or CysA7-CysB10 was formed first, and then the two other disulfide bonds were formed by iodine oxidation. The conditions for the iodine oxidation were improved to suppress oxidative degradation of unprotected Trp residues. With these conditions, bombyxin-II was synthesized in high yields (26% and 32%). Its disulfide bond isomers were also obtained. Specific activity of the products indicates that the disulfide bond CysA20-CysB22 is important to the bombyxin activity.
Pedro M Sasia - One of the best experts on this subject based on the ideXlab platform.
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synthesis of cationic flocculants by the inverse microemulsion copolymerization of acrylamide with 60 2 acryloxyethyltrimethyl ammonium chloride in the monomer feed i initiation by ammonium persulfate sodium Disulfite redox system
Journal of Applied Polymer Science, 2007Co-Authors: F Escudero J Sanz, J Ochoa R Gomez, Pedro M Sasia, Diaz E De Apodaca, P RioAbstract:Acrylamide/2-acryloxyethyltrimethyl ammon-ium chloride copolymers in inverse microemulsion, with a cationic charge density of 60% and a concentration of active matter of 30 wt %, of interest as flocculants have been obtained by inverse microemulsion copolymerization. Interesting inverse microemulsion formulations from both industrial and economical standpoints were selected from pseudoternary phase diagrams. These formulations were polymerized by semicontinuous free radical copolymerization in inverse microemulsion using sodium Disulfite and ammonium persulfate as initiators. Influence of initiators and initiator addition conditions (specific flow rate and concentration) on semicontinuous polymerization and final product properties as flocculants have been studied. A strong difference in copolymer solution viscosity has been found when an aqueous solution of sodium Disulfite is used as initiator instead of sodium Disulfite/ammonium persulfate couple redox, specially for low sodium Disulfite solution feeding flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2826–2836, 2007
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Synthesis of cationic flocculants by the inverse microemulsion copolymerization of acrylamide with 60% 2‐acryloxyethyltrimethyl ammonium chloride in the monomer feed. I. Initiation by ammonium persulfate/sodium Disulfite redox system
Journal of Applied Polymer Science, 2006Co-Authors: F. J. Escudero Sanz, Pedro M Sasia, J. R. Ochoa Gómez, E. Díaz De Apodaca, P RioAbstract:Acrylamide/2-acryloxyethyltrimethyl ammon-ium chloride copolymers in inverse microemulsion, with a cationic charge density of 60% and a concentration of active matter of 30 wt %, of interest as flocculants have been obtained by inverse microemulsion copolymerization. Interesting inverse microemulsion formulations from both industrial and economical standpoints were selected from pseudoternary phase diagrams. These formulations were polymerized by semicontinuous free radical copolymerization in inverse microemulsion using sodium Disulfite and ammonium persulfate as initiators. Influence of initiators and initiator addition conditions (specific flow rate and concentration) on semicontinuous polymerization and final product properties as flocculants have been studied. A strong difference in copolymer solution viscosity has been found when an aqueous solution of sodium Disulfite is used as initiator instead of sodium Disulfite/ammonium persulfate couple redox, specially for low sodium Disulfite solution feeding flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2826–2836, 2007
J. A. Kelber - One of the best experts on this subject based on the ideXlab platform.
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A Comparative Study of the Corrosion of Tin‐Free Steel and Iron in Sodium Bisulfite
Journal of The Electrochemical Society, 1995Co-Authors: G. Seshadri, K. A. Bower, R. W. Brooks, J. A. KelberAbstract:The authors have examined the electrochemical behavior of tin-free steel chromium type (TFS-CT) and polycrystalline iron electrodes in sodium bisulfite containing Perchlorate and nitrate solutions. Their experiments indicate that TFS-CT corrodes on exposure to sodium bisulfite. The extent to which passivation is prevented depends on the supporting electrolyte. A very interesting feature that the authors have observed is that TFS-CT exhibits a ``memory`` of exposure to sodium bisulfite, in that it does not repassivate when subsequently cycled in a bisulfite-free supporting electrolyte. This ``memory effect`` and the extent of corrosion depend on the supporting electrolyte used. Polycrystalline iron electrodes on the other hand, corrode on exposure to sodium bisulfite, but repassivate when returned to a supporting electrolyte that is free of bisulfite. The results indicate that bisulfite attacks the protective chrome oxide coating partially or completely, inhibiting subsequent passivation even in bisulfite-free electrolytes. The results also indicate that reactions of the bisulfite exposed surface with Perchlorate or nitrate anions significantly affect corrosion behavior.