LIMITED TRYPTIC HYDROLYSIS OF LEGUMIN FROM FABA BEAN (VICIA-FABA L) -FORMATION OF AN UNEQUAL SUBUNIT PATTERN

One-dimensional and two-dimensional SDS-PAGE and Hydrophobic Cluster A nalysis (HCA) were used for investigating the course of limited trypti c hydrolysis of faba bean legumin. SDS-PAGE revealed the formation of an ''unequal'' subunit pattern, characterized by 30 and 50 kDa subunit s, which could be related to the A- and B-type subunits of legumin. Th ese followed different pathways during the non-cooperative part of the tryptic hydrolysis. HCA revealed structural differences between the s ubunit types and gave arguments to predicted potential sites. A- and B -subunits differ in extension and composition of the flexible segments as well as in the interior of the C-terminal side, as in the C-termin i of the alpha-chains which confirmed the observed non-uniform hydroly sis pattern. The HCA plot demonstrated that the number and exposition of flexible surface elements was changed by limited hydrolysis. This r esult was discussed with regard to the influence of tryptic modificati on on the emulsifying properties of legumin.