FUNGAL METABOLITES .10. THE EFFECT OF PEPTIDE ANTIBIOTICS, TRICHOSPORIN-BS, ON THE RESPIRATORY ACTIVITY OF MITOCHONDRIA

The effect of the trichosporin-Bs, peptide antibiotics, on the respira tion of mitochondria was investigated. Trichosporin-Bs stimulated the respiratory rate of state 4 rat liver mitochondria in a dose-dependent manner. The maximum respiratory rate obtained by trichosporin-Bs was essentially the same as for 2,4-dinitrophenol and SF6847. Trichosporin -B-VIb released oligomycin-inhibited respiration of mitochondria. This means that trichosporin-Bs are uncouplers of oxidative phosphorylatio n. The stimulatory effect of trichosporin-B-VIb, a component of tricho sporin-Bs, on mitochondrial respiration was increased by inorganic pho sphate but not by other permeant anions studied. These results suggest that the stimulation of mitochondrial respiration by trichosporin-B-V Ib is mediated by the same mechanism as is operating in the case of hy pelcins and alamethicins. Furthermore, the relative potencies of trich osporin-Bs on the mitochondrial respiration and their relative hydroph obicities were examined. A clear relationship was observed between the uncoupling potencies of trichosporin-Bs and their relative hydrophobi cities.