251. Relationship between structure and substrate-chain-length specificity of mitochondrial very-long-chain acyl-coenzyme A dehydrogenase.
- Author
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Souri M, Aoyama T, Yamaguchi S, and Hashimoto T
- Subjects
- Acyl Coenzyme A metabolism, Acyl-CoA Dehydrogenase, Long-Chain chemistry, Acyl-CoA Dehydrogenase, Long-Chain genetics, Alanine metabolism, Base Sequence, Cells, Cultured, DNA Primers, Humans, Lipid Metabolism, Inborn Errors enzymology, Mutagenesis, Site-Directed, Protein Conformation, Substrate Specificity, Acyl-CoA Dehydrogenase, Long-Chain metabolism, Mitochondria, Liver enzymology
- Abstract
Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) is one of four enzymes which catalyze the initial step of the mitochondrial beta-oxidation with different but overlapping substrate-chain-length specificities. A450P, a variant of VLCAD identified in a patient with VLCAD deficiency, showed abnormal substrate-chain-length specificity. Based on this mutation, we studied the relationship between the structure and substrate-chain-length specificity of VLCAD. When VLCAD was treated with trypsin, a homodimer protein of a 48-kDa polypeptide deprived of both the amino-terminal 22 amino acids and the carboxyl-terminal 145 amino acids of VLCAD was obtained. Six Ala450 variants and tryptic-VLCAD exhibited similar substrate specificities. Effects of long-chain acyl-CoA on the tryptic cleavage and changes in the catalytic properties by deprivation of the carboxyl-terminal region suggest that this region interacts with the fatty acyl moiety of long-chain acyl-CoA. Thus, both Ala450 and the carboxyl-terminal region, which are not shared by other acyl-CoA dehydrogenases, are likely to be the determinating factors in the substrate-chain-length specificity of VLCAD.
- Published
- 1998
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