Phospholipid and protein metabolism in mouse liver mitochondria during riboflavin deficiency and recovery.

Abstract

A study was made of the effect of riboflavin deficiency and recovery upon the structure and function of mitochondrial membranes in mouse liver. In the deficient animals the mitochondria were enlarged and contained reduced numbers of inner membrane profiles. The activity of enzymes of the inner membranes (succinate cytochrome c reductase, cytochrome oxidase) was reduced in the deficient mitochondria, as was the content of diphosphatidylglycerol, an inner membrane phospholipid; monoamine oxidase, a mitochondrial outer membrane enzyme, and the coupling reactions of oxidative phosphorylation did not appear to be affected. Incorporation in vivo of 32Pi into phospholipids and of 3H-leucine into proteins of deficient mitochondria was normal or somewhat enhanced. Following the administration of riboflavin to the deficient mice, liver mitochondria appeared to undergo division, and inner membrane profiles seemed more numerous. Riboflavin administration increased the 3H labelling of tightly bound mitochondrial proteins, and decreased the 32P labelling of the phosphatidylcholine fraction.