Abstract:

The aggregation of the hydrolysates of soy protein isolate(sPI)induced by subtilisin protease was inves-tigated.Th e amino acid composition of the aggregates and the interaction involved in the aggregation was also dis-cussed．It is indicated by the SDS-PAGE(Sodium Dodecyl Sulphate-Polyacrylamide Gel Electropharesis)and the SE-HPLC(Size Exclusion-High Performance Liquid Chromatography)analyses that SPI is digested to small fragments with the molecular mass less than 6.5 ku,which are the major fragments involved in the aggregates.More-over,the obtained aggregates can be solubilized in buffers such as urea,guanidine hydrochloride and SDS,but can hardly solubilized in-mercaptoethanol.As revealed by the amino acid analysis,the content of the hydrophobic amino acid in the aggregates is greater than that in SPI,which suggests that(1)the hydrophobic interaction force is the major force to drive the aggregation;(2)hydrogen bonds and electrostatic forces play a role in the stabiliza-tion of the finally-formed aggregates;and(3)disulfide bonds hardly contribute to the aggregation.The mechanism 0I’the aggregation of the peptides derived from SPI induced by subtilisin protease is also discussed in this Daper in term s of the molecular structure of protein.

Key words: soy protein isolate, subtilisin protease, aggregation, interaction, mechanism