Efficient Tryptic Hydrolysis of Aryl Esters with a Cationic Center in the Leaving Group. Further Characterization of"Inverse Substrates"

The kinetic properties of esters derived from guanidinophenol and aminomethylphenol were investigated with trypsin. These compounds, in which the site-specific groups (positive charge) are of the inverse type compared with normal substrates, were demonstrated to be specific substrates, like amidinophenyl esters. The behavior of these"inverse substrates"with trypsin and pseudotrypsin was also compared. A dramatic decrease in the efficiency of hydrolysis of the"inverse substrates"by pseudotrypsin as compared to that by trypsin was observed, which was comparable in extent to that observed for specific normal-type substrates. All these observations confirm the view that specific interaction between the positive charge at the leaving moiety of"inverse substrates"and the anionic site of the trypsin active center is an essential feature of the catalysis, just as in the case of normal-type substrates.