title: Stereospecificity of malonyl-CoA decarboxylase, acetyl-CoA carboxylase, and fatty acid synthetase from the uropygial gland of goose.
abstract: Malonyl-CoA decarboxylase from the uropygial gland of goose decarboxylated (R,S)-methylmalonyl-CoA at a slow rate and introduced 3H from [3H]2O into the resulting propionyl-CoA. Carboxylation of this labeled propionyl-CoA by propionyl-CoA carboxylase from pig heart and acetyl-CoA carboxylase from the uropygial gland completely removed 3H. Repeated treatment of (R,S)-[methyl-14C]methylmalonyl-CoA with the decarboxylase converted 50% of the substrate into propionyl-CoA, whereas (S)-methylmalonyl-CoA, generated by both carboxylases, was completely decarboxylated. Radioactive (R)- (S), and (R,S)-methylmalonyl-CoA were equally incorporated into fatty acids by fatty acid synthetase from the uropygial gland. The residual methylmalonyl-CoA remaining after fatty acid synthetase reaction on (R,S)-methylmalonyl-CoA was also racemic. These results show that: (a) the decarboxylase is stereospecific, (b) replacement of the carboxyl group by hydrogen occurs with retention of configuration, (c) acetyl-CoA carboxylase of the uropygial gland generates (S)-methylmalonyl-CoA from propionyl-CoA, and (d) fatty acid synthetase is not stereospecific for methylmalonyl-CoA.
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D002262:Carboxy-Lyases / Q000378:metabolism*; D064429:Fatty Acid Synthases / Q000378:metabolism*; D005777:Geese; D008025:Ligases / Q000378:metabolism*; D008314:Malonates; D008316:Malonyl Coenzyme A; D011485:Protein Binding; D012627:Sebaceous Glands / Q000201:enzymology*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D002250:Carbon Radioisotopes; D008314:Malonates; D008316:Malonyl Coenzyme A; D064429:Fatty Acid Synthases; D002262:Carboxy-Lyases; C021532:malonyl-CoA decarboxylase; D008025:Ligases; D000103:Acetyl-CoA Carboxylase