Inhibition of Chymotrypsin by Diethyl p-Nitrophenyl Phosphate

Abstract

CHYMOTRYPSIN displays both esterase and proteolytic activity, and it has recently been shown¹ that this enzyme is inhibited by diisopropyl fluorophosphonate and that loss of esterase activity is paralleled by loss of proteolytic activity. Diethyl p-nitrophenyl phosphate (E.600) resembles diisopropyl fluorophosphonate in being a very powerful anticholinesterase. We have found that it will also inhibit chymotrypsin, and have been studying the system chymotrypsin–diethyl p-nitrophenyl phosphate as a convenient model for other esterase systems, since the physical data for this enzyme (purity, molecular weight, etc.) are among the more accurately known.