Effects of some antibiotics on pyruvate decarboxylase (Enzyme and recombined holoenzyme)

Abstract

Pyruvate decarboxylase (4.1.1.x.) is inhibited by most of the antibiotics tested. The effect on the recombined holo­enzyme system is normally higher than on the purified enzyme. Results found in vitro with propionyl erythromycin and phenoxi-methyl-penicillin are remarkably different from those obtained with other derivatives of the same molecules, showing the influence of little Chemical modifications of the antibiotic structure on its effect. Pheno- ximethyl-penicillin, colimycin metansulfonate, novobiocin, ristocetin, spyramycin, tricomycin and griseofulvin act by noncompetitive mechanisms. Inhibitory action of glycosidic-type antibiotics (kanamycin excepted) is especially high on the pyruvate decarboxylase. Tetracyclines, vancomycin and risto­cetin act at the level of metal cofactor requirement as shown by results obtained in previous incubations with the components of the holoenzyme system. The presence of substrato usually prevents the effect produced by compounds with chelating properties. Cycloserine, kanamycin, erithromycin and oleandomycin have no effect on the enzyme activity under the conditions of the experiments.