MAPLE SYRUP URINE DISEASE - BRANCHED-CHAIN KETO ACID DECARBOXYLATION IN FIBROBLASTS AS MEASURED WITH AMINO-ACIDS AND KETO ACIDS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 29  (3) , 272-279
Abstract
Branched-chain keto acid decarboxylase activity in skin fibroblasts from control subjects and from patients with classical and variant forms of maple syrup urine disease subjects and from patients with classical and variant forms of maple syrup urine disease (MSUD) was measured with leucine and .alpha.-ketoisocaproic acid. When the keto acid was used as substrate in high concentrations (more than 5 mM), the 3 groups overlapped extensively, even classical cases of MSUD exhibiting decarboxylase activity. With leucine as substrate, decarboxylase activity plateaued at about 1.5 mM, and the 3 groups could be clearly differentiated. Classical cases of MSUD had minimal or no decarboxylase activity.