Effect on organic acid metabolism with high intake of leucine and biotin deficiency in mice

Abstract

Biotin belongs to the one of the water-soluble vitamin B groups, and it is a cofactor of carboxylase, such as acetyl-CoA carboxylase (ACC), pyruvate carboxylase (PC), propionyl-CoA carboxylase (PCC) and 3-methylcrotonyl-CoA carboxylase (MCC). 3-Hydroxyisovaleric acid (3-HIA) which is a metabolite of leucine catabolism is a kind of organic acid in urine. The leucine degradation pathway often works to create acetyl-CoA and acetoacetate. When biotin is deficient, an alternative metabolic pathway produces 3-HIA. In this study, when the activity of 3-methylcrotonyl-CoA carboxylase decreased, 3-HIA excretion increased in the urine. The urinary excretion of 3-HIA was determined by HPLC. Feeding an additional two-fold increase of leucine had no effect on urinary 3-HIA but urinary biotin was increased due to the leucine. In addition, leucine had effects on relative weight and biotin levels in some tissues. From these findings, although 3-HIA is a sensitive indicator of biotin deficiency, we have to pay attention when evaluating biotin deficiency.