Qingqing Yu,Tong Shi,Zhiyu Xiong,Li Yuan,Hui Hong,Ruichang Gao,Yulong Bao
In order to study the effect of oxidation on the dye-binding behavior of myofibrillar proteins, selected dyes with different charges (positively charged Sarfarin O (SO), neutral bromophenol blue (BPB), and negatively charged Orange G (OG)) were incubated with myofibrils oxidized by the Fenton system with H 2 O 2 (10 mM). Upon oxidation, loss of free thiols, formation of carbonyls, particle size, and hydrophobicity of myofibrillar proteins (MPs) increased. The absolute value of Zeta-potential increased by 14.48 % after oxidation, the myofibrillar proteins shifted to a more acidic isoelectric point (pI) upon oxidation. Oxidation decreased net positive charges of myofibrillar protein and the binding ability of MPs towards OG in the environment with pH less than pI and the affinity of MPs towards SO in the environment with pH more than pI were thus increased. Here we propose a hypothesis that oxidation-induced change in net charges is the driving force affecting the amount of protein-bound dye. This paper aims to examine the effect of oxidation on the net charges of myofibrillar proteins and to provide insight into the mechanism of oxidation-induced changes in protein-bound dyes.
Heavy oil exploitation needs efficient viscosity reducers to reduce viscosity, and polyether carboxylate viscosity reducers have a significant viscosity reduction effect on heavy oil. Previous work has studied the effect of different side chain lengths on this viscosity reducer, and now a series of polyether carboxylate viscosity reducers, including APAD, APASD, APAS, APA, and AP5AD (the name of the viscosity reducer is determined by the name of the desired monomer), with different electrical properties have been synthesized to investigate the effect of their different electrical properties on viscosity reduction performance. Through the performance tests of surface tension, contact angle, emulsification, viscosity reduction, and foaming, it was found that APAD viscosity reducers had the best viscosity reduction performance, reducing the viscosity of heavy oil to 81 mPa·s with a viscosity reduction rate of 98.34%, and the worst viscosity reduction rate of other viscosity reducers also reached 97%. Additionally, APAD viscosity reducers have the highest emulsification rate, and the emulsion formed with heavy oil is also the most stable. The net charge of APAD was calculated from the molar ratio of the monomers and the total mass to minimize the net charge. While the net charge of other surfactants was higher. It shows that the amount of the surfactant’s net charge affects the surfactant’s viscosity reduction effect, and the smaller the net charge of the surfactant itself, the better the viscosity reduction effect.
Transglutaminase (TGase) is a widely utilized biocatalyst in the food industry, where it catalyzes the cross-linking of proteins in protein-rich foods, leading to improved texture and enhanced functional properties. Currently, commercially available TGases are derived from Streptomyces species. To expand the industrial application potential of TGase, this study employed a combined sequence- and structure-based strategy to identify a novel TGase from Krasilnikovia cinnamomea (KcTG). The enzyme was successfully heterologously expressed in Escherichia coli, exhibiting an optimal temperature of 60 °C and a maximum specific activity of 42.17 U/mg, outperforming SmTG. Furthermore, KcTG demonstrated efficient cross-linking of soy protein isolate, positioning it as a promising candidate for future industrial TGase enzyme preparations. This study also integrated computational tools to analyze the structural characteristics of KcTG based on surface net charge and hydrophobicity. Additionally, molecular dynamics (MD) simulations were employed to investigate its stability and catalytic performance.
危险品化学品经营许可证（带存储）