Repression of Pyruvate Kinase in Candida utilis and Rat Liver by Sclerin through Energy Charge

Abstract

Though sclerin (SCL) only slightly inhibited the activity of pyruvate kinase (PK) in crude extract of Candida utilis, markedly repressed the level of that in the growing cells in a glucose medium. The repression of PK was largely recovered by 2, 4-dinitrophenol (DNP), and SCL rather raised the level in the cells growing on gluconate.
SCL also slightly inhibited the activity of a partially purified PK from rat liver, and, when orally administered, or incubated with the liver slices, obviously lowered the level of PK in the liver and liver slices. The effect of SCL in the liver slices was reversed by DNP. SCL stimulated the oxidative phosphorylation in mitochondria prepared from the fresh liver, and served to maintain the activity in the liver slices during incubation.
Both activity of PK from Candida utilis and rat liver was remarkably inhibited by adenylate energy charge in vitro.
It is concluded that SCL represses the level of PK in these cells and tissues through a high energy charge by stimulating the oxidative phosphorylation.