Characteristics of hepatic alanine-glyoxylate aminotransferase in different mammalian species

T. Noguchi, E. Okuno, Y. Takada, Y. Minatogawa, K. Okai, R. Kido

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Abstract

Mitochondrial extracts of dog, cat, rat and mouse liver contain two forms of alanine-glyoxylate aminotransferase (EC 2.6.1.44): one, designated isoenzyme 1, has mol wt. approx. 80000 and predominates in dog and cat liver; the other, designated isoenzyme 2, has mol. wt. approx. 175,000 and predominates in rat and mouse liver. In rat and mouse liver, isoenzyme 1 activity was increased by the injection in vivo of glucagon, but not isoenzyme 2 activity. Isoenzyme 1 was purified and characterized from liver mitochondrial extracts of the four species. Both rat and mouse enzyme preparations catalysed transamination between a number of L-amino acids and glyoxylate, and with L-alanine as amino donor the effective amino acceptors were glyoxylate, phenylpyruvate and hydroxy-pyruvate. In contrast, both dog and cat enzyme preparations were specific for L-alanine and L-serine with glyoxylate, and used glyoxylate and hydroxypyruvate as effective amino acceptors with L-alanine. Evidence that isoenzyme 1 is identical with serine-pyruvate aminotransferase (EC 2.6.1.51) was obtained. Isoenzyme 2 was partially purified from mitochondrial extracts of rat and mouse liver. Both enzyme preparations were specific for L-alanine and glyoxylate. On the basis of physical properties and substrate specificity, it was concluded that isoenzyme 2 is a separate enzyme. Some other properties of isoenzymes 1 and 2 are described.

Original languageEnglish
Pages (from-to)113-122
Number of pages10
JournalBiochemical Journal
Volume169
Issue number1
Publication statusPublished - 1978
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

Cite this

Noguchi, T., Okuno, E., Takada, Y., Minatogawa, Y., Okai, K., & Kido, R. (1978). Characteristics of hepatic alanine-glyoxylate aminotransferase in different mammalian species. Biochemical Journal, 169(1), 113-122.