Two proteases from nuclei of rat testis cells. II. Inhibitors

Proteases R c and K c of the nuclei of rat testis cells exhibit considerable differences in susceptibility to various protease inhibitors. Protease R c is inhibited by D-phenylalanyl-L-propyl-L-arginine chlormethylketone and p-nitrophenyl-p 1 -guanidino ben-zoate. Protease K c is inhibited by Nα-p-tosyl-L-lysine chlormethylketone, N-p-tosyl-phenylalanine chlormethylketone, N-carbobenzoxy-L-phenylalanine chloromethylketone and p-nitrophenyl-p'-guanidino-benzoate. Neither protease is inhibited by 10 mM phenylmethanesulphonyl-fluoride or p-chloromercuri-benzoate. p-nitrophenyl-p 1 -guanidino-benzoate is a substrate for protease R c with release of p-nitrophenol, however the protease activity is not restored during a period of 8 hours after removal of excess p-nitrophenyl-p 1 -guanidino-benzoate. Both proteases can bind to immobilized soybean trypsin inhibitors.