Specificity and reactivity of human granulocyte elastase and cathepsin G, porcine pancreatic elastase, bovine chymotrypsin and trypsin toward inhibition with sulfonyl flourides

Abstract

Human granulocyte elastase (EC 3.4.21.11) and cathepsin G (EC 3.4.21.20), porcine pancreatic elastase (EC 3.4.4.7), and bovine chymotrypsin-A α (EC 3.4.4.3) and trypsin (EC 3.4.4.4) are inhibited by aryl and alkyl sulfonyl fluorides at different rates. The 26 000-fold variance in inhibition rates reflects the intrinsic reactivity and specificity differences of these closely related serine proteases. Human granulocyte elastase is inhibited more rapidly than porcine pancreatic elastase by all of the sulfonyl flourides studied. In contrast, human cathepsin G. reacts more slowly with the series of sulfonyl flourides than does bovine chymotrypsin-A α. Trypsin is the least reactive of the five enzymes, reflecting its relatively more stringent specificity requirements. Reagents such as CH 3SO 2F, 4-CH 3C 6H 4SO 2F, 3-CH 3COC 6H 4SO 2F and 2-NH 2C 6H 4SO 2F exhibit little or no selectivity toward the five enzymes studied. On the other hand, phenylmethane sulfonyl fluoride shows a range of reactivity of 137-fold toward the various proteases and is most reactive with bovine chymotrypsin-A α. The peptide sulfonyl fluoride 2-(Ac-Ala-Ala-NHN(CH 3)CONH)C 6H 4SO 2F had a reactivity range of 41, with granulocyte elastase being inhibited most rapidly. Although none of the sulfonyl fluorides are completely specific, the examples reported in this paper show that structural changes have considerable potential for increasing both the selectivity of sulfonylating agents toward various serine proteases and their reactivities.