Fungal metabolites. X. The effect of peptide antibiotics, trichosporin-Bs, on the respiratory activity of mitochondria.

The effect of the trichosporin-Bs, peptide antibiotics, on the respiration 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 phosphorylation. The stimulatory effect of trichosporin-B-VIb, a component of trichosporin-Bs, on mitochondrial respiration was increased by inorganic phosphate but not by other permeant anions studied. These results suggest that the stimulation of mitochondrial respiration by trichosporin-B-VIb is mediated by the same mechanism as is operating in the case of hypelcins and alamethicins. Furthermore, the relative potencies of trichosporin-Bs on the mitochondrial respiration and their relative hydrophobicities were examined. A clear relationship was observed between the uncoupling potencies of trichosporin-Bs and their relative hydrophobicities.