Purification and characterization of a cysteine proteinase involved in globulin hydrolysation in germinatedVicia fabaL.

Abstract

A cysteine proteinase (EC 3.4.22.-), present in high amounts in the cotyledons of germinated seeds of Vicia faba L. 14 d after imbibition, was purified to homogeneity based on one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional PAGE (isoelectric focusing followed by SDS-PAGE). The proteinase has an apparent molecular mass of 31 kDa, an isoelectric point of 4.5, has optimal activity at pH 5.0-5.5 and 30-40 o C. Classification as a cysteine proteinase was determined via the effects of numerous proteinase inhibitors on the activity of the enzyme against the synthetic substrate azocasein