Productive and nonproductive substrate binding in enzyme mimics

Hydrolytic activity of molecularly imprinted polymeric mimics of chymotryps in was evaluated against N-acetyl tyrosyl pam nitrophenyl ester and N-benzo yl tyrosyl para nitrophenyl ester, respectively. The mimic grafted on hydro philic support exhibited high k(cat) and high K-m values for N-acetyl tyros yl para nitrophenyl ester. But, for N-benzoyl tyrosyl pam nitrophenyl ester , the mimic exhibited low k(cat) as well as low K-m values, consistent with the nonproductive binding exhibited by natural chymotrypsin for hydrophobi c substrate. The same mimic when grafted on hydrophobic support exhibited t rends consistent with Michaelis-Menten kinetics and also higher catalytic a ctivity than that exhibited by the mimic on hydrophilic support. Thus in th e case of mimics nonproductive substrate binding could be eliminated by the choice of appropriate support. This helped to enhance the mimic activity t owards a specific substrate. This discretion is not available in the case o f native enzyme. (C) 1999 Elsevier Science Ltd. All rights reserved.