大豆球蛋白的热聚集机理与二硫键还原动力学研究

his work aims to explain the contributes of SH/SS exchange and SH oxidation occurred among different subunits/polypeptides on the formation of SS linked products, as well as the effects on reduction kinetics of the intra-chain and inter-chain disulfide bonds in heated 11S, through analyzing the subunit composition of heating products. Comparison of the subunit composition of the heat induced products of 11S treated by NEM for different hours demonstrates that the sulfhydryl residue on basic polypeptides could be an initiator to the thermal aggregation. SH/SS exchange and SH oxidation are prevented under the condition that the sulfhydryl residues were completely blocked. The 11S intra-chain disulfides reduced faster than inner-chain disulfides. While heating of the sulfhydryl blocked 11S, the subunits preserved and inter-chain disulfide bonds gradually exposed as the polypeptides unfolded, resulting in the constant reduction rate of intra-chain disulfide bonds and the increasing reduction rate of inter-chain disulfide bonds. As for the unblocked 11S, the reduction rate of both intra-chain and inter-chain disulfide bonds decrease after heat treatment because of the increase on the size of aggregates and the amount of dimer of basic polypeptides as well as the formation of hydrophobic core.