Studies on the Microsomal Electron-transport System of Anaerobically Grown Yeast

Abstract

A b-type cytochrome previously called cytochrome b₁ was localized in the microsomes from anaerobically grown yeast cells. The cytochrome was solubilized from, the microsomes by tryptic digestion, and was highly purified. The spectral properties of the cytochrome agreed well with those of cytochrome bt from liver microsomes. Molecular weight, midpoint oxidation-reduction potential and net charge of the purified cytochrome were also similar to those of cytochrome b₅ purified from rat liver microsomes by similar procedures. The purified cytochrome could be reduced by NADH-cytochrome b₅ reductase [EC 1.6. 2. 2] from mammals. The results indicated that the cytochrome should be named cytochrome b_5M of yeast.