Inhibition of trypsin by t-Butyloxycarbonyl-α-aza-(4-aminophenyl)alanine phenyl ester

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Abstract
T‐Butyloxycarbonyl‐α‐aza‐(4‐aminophenyl)alanine phenyl ester (Fig. 1, III: R = NH2) has been synthesized. The rate of inhibition of trypsin (EC 3.4.21.4) by this compound (due to acylation followed by slower deacylation) shows a marked pH maximum at approximately 6. The shape of the pH—rate curve is discussed in terms of (i) the normal pH—activity curve of trypsin reacting with a charged substrate, i.e. the protonated form of the amino compound, (ii) the deprotonation of the 4‐amino group with pKa 4·3, and (iii) the lower rate of reaction of the enzyme with the uncharged, deprotonated form of the ester.