[Vitamin B6 dependency syndrome].
Many enzymes that require pyridoxal 5'-phosphate (PLP), a coenzyme from a vitamin B6, are involved in amino acid metabolism. B6 dependency syndromes are defined as a group of metabolic disorders which are prevented or alleviated by non-physiologically large doses of vitamin B6, and, hence, they are tacitly accounted for by some structural alteration in a responsible B6-dependent enzyme such as a decrease on the affinity for PLP as compared to the normal. In this article, the mode of binding the coenzyme is exemplified by the case of aspartate aminotransferase, a typical B6-dependent enzyme whose three-dimensional structure is known, and, several B6 dependency syndromes are briefly reviewed. Among these syndromes, the molecular basis of only gyrate atrophy has recently been defined by the identification of a mutation in the relevant enzyme, ornithine aminotransferase.
Tanase
S
S
Department of Biochemistry, Kumamoto University Medical School.
Morino
Y
Y
D000592:Amino Acid Metabolism, Inborn Errors / Q000209:etiology / Q000378:metabolism*; D001219:Aspartate Aminotransferases / Q000172:deficiency*; D003540:Cystathionine / Q000652:urine; D006712:Homocystinuria; D006801:Humans; D006959:Hyperoxaluria; D009952:Ornithine / Q000097:blood*; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011736:Pyridoxine / Q000378:metabolism / Q000502:physiology*
D003540:Cystathionine; D011732:Pyridoxal Phosphate; D009952:Ornithine; D001219:Aspartate Aminotransferases; D011736:Pyridoxine