The effect of vitamin B6 deficiency on alanine: Glyoxylate aminotransferase isoenzymes in rat liver

Yoshikazu Takada, Toshio Mori, Tomoo Noguchi

研究成果: 雜誌貢獻文章同行評審

3 引文 斯高帕斯(Scopus)


Endogenous synthesis of oxalate has been reported to increase in vitamin B6 deficiency probably due to defective transamination of glyoxylate, the direct source of oxalate, to glycine. Alanine:glyoxylate aminotransferase (AGT) in the liver catalyzes most of the glyoxylate transamination in mammalian tissues (E. V. Rowsell, K. Snell, J. A. Carnie, and K. V. Rowsell (1972)Biochem. J.127, 155-165). The effects of vitamin B6 deficiency on hepatic AGT isoenzymes, designated AGT 1 and AGT 2, respectively, were examined with male rats; AGT 1 is located both in the peroxisomes and in the mitochondria, and AGT 2 only in the mitochondria. The holo activity of combined peroxisomal and mitochondrial AGT 1 with a low Km for l-alanine rapidly decreased after a lag time of about 2 days during feeding of the vitamin B6-deficient diet (by 50% in 5 days, by 86% in 14 days). Peroxisomal AGT 1 activity was more affected than the mitochondrial. The holo activity of AGT 2 with a high Km for l-alanine decreased more slowly than AGT 1 (by 33% in 14 days, by 60% in 28 days). Urinary excretion of oxalate began to increase in 8-9 days, when AGT 2 remained intact but most of AGT 1 is depleted. When the defect in the glyoxylate transamination in vivo in vitamin B6 deficiency is considered, these findings suggest that it is due to the deficiency of AGT 1. The importance of peroxisomal AGT 1 is discussed, since peroxisomes have been described to be probably the major site of glyoxylate formation.

頁(從 - 到)1-6
期刊Archives of Biochemistry and Biophysics
出版狀態已發佈 - 2月 15 1984

ASJC Scopus subject areas

  • 生物化學
  • 生物物理學
  • 分子生物學


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