A new variant of methylmalonic acidemia-defective coenzyme-apoenzyme binding in cultured fibroblasts.
Cultured fibroblasts from a patient with methylmalonic acidemia, clinically responsive to vitamin B-12, were studied in vitro. Kinetic analysis revealed abnormal binding of the coenzyme, 5'-deoxyadenosylcobalamin, for its methylmalonyl-CoA carbonylmutase apoenzyme, i.e., KM of 3.8 X 10(-5) M versus control KM of 1.5 X 10(-8) M. These data are interpreted as indicating a structural defect of the apoenzyme at the coenzyme binding site, and represent another variant of this genetic disorder.
D000592:Amino Acid Metabolism, Inborn Errors / Q000097:blood* / Q000201:enzymology; D002478:Cells, Cultured; D003067:Coenzymes / Q000172:deficiency* / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000097:blood* / Q000201:enzymology; D007535:Isomerases / Q000172:deficiency*; D007700:Kinetics; D008314:Malonates / Q000097:blood*; D008764:Methylmalonic Acid / Q000097:blood*; D008765:Methylmalonyl-CoA Mutase / Q000172:deficiency* / Q000378:metabolism; D011485:Protein Binding; D012867:Skin / Q000166:cytology; D014805:Vitamin B 12 / Q000378:metabolism
D003067:Coenzymes; D008314:Malonates; D008764:Methylmalonic Acid; D007535:Isomerases; D008765:Methylmalonyl-CoA Mutase; D014805:Vitamin B 12