부산대학교 도서관

To see whether kinetic assays of lipoamide dehydrogenase could be used for carrier detection or preclinical diagnosis, Michaelis-Menten constants (KmLand KmH) for the enzyme were determined in platelets from families with a form of recessive Friedreich ataxia and low activities of the enzyme. The KmLof patients' enzyme was 132 ± 5 μM lipoamide (mean ± SEM) versus 56 ± 9 μM for controls (p< 0.001), and KmHfor the patients was 421 ± 19 μM versus 147 ± 14 μM for the controls (p< 0.001). The activity and Km values of one patient's enzyme were abnormal 1 year before neurologic signs appeared. The Km values for the enzymes of the six parents were also elevated (average KmL, 105 ± 10 μM; average KmH, 378 ± 47 μM, p< 0.02). The maximal activities of the parents' enzymes, relative to a mitochondrial marker, were intermediate between the mean maximal control activity and the mean activity for the affected offspring. The data suggest that the abnormalities of lipoamide dehydrogenase are inherited in a recessive pattern in these families.