title: Potent inactivator of alpha-chymotrypsin: 2,2-dimethyl-3-(N-4-cyanobenzoyl)amino-5-phenyl pentanoic anhydride.
abstract: We synthesized a novel potent alpha-chymotrypsin inactivator, 2,2-dimethyl-3-(N-4-cyanobenzoyl) amino-5-phenyl pentanoic anhydride, which fulfilled the criteria of a mechanism-based inactivator: first-order kinetics, irreversibility, saturation kinetics and substrate protection. The inactivation rate constant (kinact) and the enzyme-inhibitor dissociation constant (KI) were calculated to be 0.017s-1 and 0.071 microM, respectively (kinact/KI = 242,000 M-1s-1). These kinetic parameters indicate that this compound is one of the most powerful alpha-chymotrypsin inactivators ever reported. The average number of alpha-chymotrypsin turnovers per inactivation (partition ratio) was calculated to be 1, which indicates that it is a stoichiometrically ideal inactivator of alpha-chymotrypsin. We compared the IC50 values of this compound with those of several chymotrypsin-like serine proteinases (bovine alpha-chymotrypsin, recombinant human chymase and human neutrophil cathepsin G) and a metallo proteinase, rabbit angiotensin converting enzyme (ACE). Our compound, 2,2-dimethyl-3-(N-4-cyanobenzoyl) amino-5-phenyl pentanoic anhydride, inhibited bovine alpha-chymotrypsin potently (IC50 = 1.0 (+/- 0.2) x 10(-9) M) as well as other chymotrypsin-like serine proteinase; recombinant human chymase (IC50 = 7.0 (+/- 1.0) x 10(-8) M) and human neutrophil cathepsin G (IC50 = 1.8 (+/- 0.2) x 10(-7) M). However, rabbit ACE was not inhibited by this compound (IC50 > 1 x 10(-4) M).
authors.affiliation: Advanced Technology Research Laboratories, Nippon Steel Co., Ltd., Kawasaki, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Igarashi
authors.forename: M
authors.initials: M
authors.lastname: Muramatsu
authors.forename: T
authors.initials: T
authors.lastname: Harada
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.forename: J
authors.initials: J
authors.lastname: Katada
authors.forename: I
authors.initials: I
authors.lastname: Uno
mesh_terms: D000812:Anhydrides / Q000138:chemical synthesis* / Q000494:pharmacology*; D000818:Animals; D001549:Benzamides / Q000138:chemical synthesis* / Q000494:pharmacology*; D056649:Cathepsin G; D002403:Cathepsins / Q000037:antagonists & inhibitors; D002417:Cattle; D053818:Chymases; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C109590:2,2-dimethyl-3-(N-4-cyanobenzoyl)amino-5-phenyl pentanoic anhydride; D000812:Anhydrides; D001549:Benzamides; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D002403:Cathepsins; D007703:Peptidyl-Dipeptidase A; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C534094:CTSG protein, human; D056649:Cathepsin G; D053818:Chymases