Interaction of dansylated peptidyl chloromethanes with trypsin, chymotrypsin, elastase, and thrombin

Abstract

A series of N.alpha.-1-(dimethylamino)-5-naphthalenesulfonyl (dansyl) derivatives of peptidyl chloromethanes (chloromethyl ketones) were synthesized and employed to introduce the fluorescent dansyl moiety specifically into the active sites of proteinases via affinity labeling. Dansylalanyllysylchloromethane (DALCM) was utilized to inactivate and fluorescently label [bovine] trypsin and the trypsin-like enzyme [bovine] thrombin. Dansylleucylphenylalanylchloromethane (DLPCM) was synthesized and selectively employed as an inhibitor of [bovine] chymotrypsin. The di-, tri- and tetrapeptides-dansylprolylalanylchloromethane (DPACM), dansylalanylpropylalanylchloromethane (DAPACM) and dansylprolylalanylprolylalanylchloromethane (DPAPACM)-were synthesized and their interaction with [porcine] elastase (EC 3.4.21.11) was evaluated. The compounds DALCM, DLPCM and DAPACM were effective, fast-acting proteinase inhibitors. Studies of energy transfer in the enzyme-inhibitor conjugates led to results entirely consistent with the proposed conformational homology of thrombin with the other serine proteinases studied. The fluorescent affinity labels are believed to possess enormous potential for the localization, isolation and characterization of enzymes.