EFFECTS OF SYNTHETIC TRYPSIN-INHIBITORS ON THE GROWTH OF ESCHERICHIA-COLI

The inhibitory effects of various aromatic esters of trans-4-guanidinomethylcyclohexanecarboxylic acid (GMCHA), potent trypsin inhibitors, on the growth of Escherichia coli were examined and the effects were compared with those of well known synthetic trypsin inhibitors. Various GMCHA esters strongly inhibited the growth of E. coli and their effects were markedly affected by the species and position of substitution on the phenyl nucleus of the GMCHA phenyl esters. No correlation was observed between the effects on the growth of E. coli and K(i)'s for trypsin. Inhibitory effects of benzamidine, phenylmethane sulfonylfluoride and diisopropyl fluorophosphate were less than 10% at 200 muM. 4-tert-Butylphenyl ester of GMCHA (GMCHA-OPh(t)Bu), a representative of various GMCHA esters, dose-dependently inhibited the growth of E. coli and the growth inhibition was preceded by a dose- and time-dependent inhibition of DNA synthesis. Tosyl-L-lysine chloromethyl ketone (TLCK) and pentamidine isethionate, potent trypsin inhibitors, also dose-dependently inhibited the growth of E. coli and the DNA synthesis. However, their effects were transient and disappeared after a short while. These results indicate that the effects of TLCK and pentamidine isethionate differ from those of GMCHA esters. GMCHA-OPh(t)Bu and pentamidine isethionate also inhibited RNA and protein synthesis.