Oxidative enzymes and phosphorylation in hepatic mitochondria from riboflavin-deficient rats.

It has been known for many years that a number of different nutritional deficiencies lower the efficiency of food utilization. For example, riboflavin-deficient rats consume 15 to ‘20% more calories than are required to maintain control animals at the same weight (1). The lowered efficiency of food utilization in riboflavin deficiency has been attributed in part to incomplete oxidation of nutrients (2, 3). However, since flavoproteins are involved in the electron transport chain, it seemed possible that riboflavin deficiency and consequent decrease in flavin enzyme activities might affect the efficiency of oxidative phosphorylation. This possibility was tested with liver mitochondria from riboflavin-deficient rats. Highly significant alterations in the activity of certain oxidative flavin enzymes, and in the efficiency of oxidative phosphorylation of riboflavin-deficient mitochondria were found. In addition, some indications of changes both in the gross mass and character of the liver mitochondria have been observed.