STUDIES ON LACTATE CYTOCHROME C REDUCTASES OF YEAST WITH SPECIAL REFERENCE TO ELECTROPHORESIS ON POLYACRYLAMIDE GEL

Abstract

Two lactate dehydrogenases, L(+)- and D(−)- lactate cytochrome c reductase, were extracted from the baker's yeast after disintegration of the cells by a FRENCH press. They are separated by electrophoresis on polyacrylamide gel and their activities were compared by color density of formazan, the reduction product of nitroblue tetrazolium. The ratio of L-lactate cytochrome c reductase activity to D-lactate cytochrome c reductase activity varied to a great extent, depending on culture conditions. L-Lactate cytochrome c reductase was predominant in resting cells; the reverse was the case with cells in early exponential stage of the growth. When the cells in exponential stage of growth were aerated without nitrogen source, there occurred an intensive increase of L-lactate cytochrome c reductase, accompanied by the decrease of D-lactate cytochrome c reductase. Effects of inhibitors on the activity ratio of these two enzymes were investigated. o-Phenanthroline, dinitrophenol, sodium azide, chloramphenicol, British antilewisite and antimycin A favored, in this order, the formation of L-lactate cytochrome c reductase.