PURIFICAREA ŞI CARACTERIZAREA PARŢIALĂ A PROTEINAZEIA DIN SEMINŢELE GERMINATE DE FASOLE

Abstract

Proteinase A, that possibly participate in the degradation of phaseolin, the main 7S storage protein of kidney bean (Phaseolus vulgarisL.), was isolated asa35 kDapolypeptide from germinating kidney bean seeds and partially charac-terised. According to its properties it belong to a group of homologous cysteine proteinases of the papain family that participate in storage protein mobilisation during seeds geminating of many plants. The proteinases of this group hydrolize storage proteins to short peptides. Dispite close similarity to proteinase A from vetch, proteinase A from kidney bean hydrolyse phaseolin by non-co-operative m echanism. This action is limited to the cleavage of subunits into two approxi-mately equal parts and to spliting off a number of short peptideswhich result in the modification of quaternary structure of phaseolin molecule. It is similar to the action on phaseolin of other proteases, both endogenous and exogenous, and provide another example of the importance of phaseolin structure in the explanation of its resistance to proteolysis.