Collect. Czech. Chem. Commun. 1980, 45, 442-451

N-Acylated phenylalanine p-nitroanilides: New substrates for chymotrypsin

Evžen Kasafíreka and Michal Bartíkb

a Research Institute for Pharmacy and Biochemistry, 130 60 Prague 3
b Department of Biochemistry and Toxicology, Institute of Veterinary, 041 81 Košice


Chromogenic substrates of the following types were synthesized: X-Phenylalanine p-nitroanilides, where X = acetyl, hydroxyacetyl, methoxyethoxyacetyl, and 3-carboxy-2-propenoyl, (glycyl)n-phenylalanine p-nitroanilides and 3-carboxypropanoyl(glycyl)n-phenylalanine p-nitroanilides, where n = 1,2,3, (glycyl)n-tyrosine p-nitroanilides and 3-carboxypropanoyl(glycyl)n-tyrosine p-nitroanilides, where n = 0,1,2, and also acetylhistidyl-glycyl-glycyl-phenylalanine p-nitroanilide. The constants Km, kcat and C (i.e. kcat/Km) were estimated for enzymic splitting by chymotrypsin. The greatest kcat values were found for 3-carboxypropanoylglycyl-glycyl-tyrosine p-nitroanilide and 3-carboxypropanoyl-glycyl-glycyl-phenylalanine p-nitroanilide, 40.5 and 16.9, respectively. The smallest Km value, 1.1 x 10-4 (mM) was observed with acetylhistidylglycyl-glycyl-phenylalanine p-nitroanilide, which exhibited also the greatest C constant, 115 000 (M-1 s-1).