THE ROLE OF INTERLINKED POSITIVE CHARGES IN THE POLYCATION INHIBITIONOF A LEAF PROTEINASE

The role of the degree of polymerization and of interlinked positively charged groups in the mechanism of inhibition of a proteinase purifie d from alfalfa (Medicago sativa) leaf by polycations has been investig ated using L-lysine oligomers as model. The monomer, dimer and trimer show competitive inhibition, do not induce conformational change of th e enzyme molecule and are not sensitive to ionic strength; the pentame r shows a mixed type of inhibition and induces a conformational change in the enzyme molecule. Both pentamer inhibition and conformational c hange are ionic strength dependent.