Abstract
Alanine: gamma, delta-dioxovalerate aminotransferase had been purified from bovine liver mitochondria, and the capacity of this enzyme to form delta-aminolevulinic acid had been suggested to be far greater than that of delta-aminolevulinate synthase (EC 2.3.1.37) from the same mitochondria (Varticovski, L., Kushner, J. P., and Burnham, B. F. (1980) J. Biol. Chem. 255, 3742-3747). In the present study, alanine: gamma, delta-dioxovalerate aminotransferase and alanine-glyoxylate aminotransferase (EC 2.6.1.44) were co-purified to homogeneity from bovine liver mitochondria. The ratio of the two activities remains constant during purification and is unchanged by a variety of treatments of the purified enzyme. Alanine: gamma, delta-dioxovalerate aminotransferase activity is competitively inhibited by glyoxylate. Some kinetic data are presented. These results show that the two activities are associated with the same protein. The enzyme is much higher in the glyoxylate aminotransferase activity than in the dioxovalerate aminotransferase activity. The purified enzyme has a molecular weight of approximately 240,000 with four identical subunits and an isoelectric point of 5.4. The ratio of the gamma, delta-dioxovalerate aminotransferase activity to the glyoxylate aminotransferase was determined with alanine:glyoxylate aminotransferase preparations from various mammalian liver and kidney.
Highlights
Alanin ey:, S - dioxovalera taem inotransferase had sively via a transamination reaction between L-alanine and been purified from bovine liver mitochondria, and the y,6-dioxovalerate [5,6,7,8];6-aminolevulinic acidsynthase has not capacity of this enzyme to f o r m 8-aminolevulinic acid been demonstrated in plant leaves [5, 6]
At each stage in the purification, the same mitochondria, suggesting the possibility that the alanine:y,S-dioxovalerateaminotransferase and a1anine:glyoxylate enzyme plays a role in the biosynthesis of 6-aminolevulinic aminotransferase activities were determined.Both activities were acid in vivo [4]
These results show that thetwo aminotransferases areassociated with the mitochondria
Summary
From the Departmentof Biochemistry, Kyushu Dental College, Kokura, Kitakyushu 803, Japan. Alanine:y,S-dioxovalerate aminotransferase and alanine-glyoxylate aminotransferase (EC 2.6.1.44) were co-purified to homogeneity from bovine liver mitochondria. At each stage in the purification, the same mitochondria, suggesting the possibility that the alanine:y,S-dioxovalerateaminotransferase and a1anine:glyoxylate enzyme plays a role in the biosynthesis of 6-aminolevulinic aminotransferase activities were determined.Both activities were acid in vivo [4]. Theconcentrated enzyme solution was subjectedto isoelectric focusing on a pH 3.0-10 Pharmalyte gradient,as described by Vesteractivity ratio, y,S-dioxovalerate aminotransferase/glyoxylate aminotransferase, remained constant during thepurification. These activities were not increased by the addition of pyridoxal 5”phosphate (0-40 ELM),showing the presence of the holoenzyme. The isoenzymes 2 of monkey, chicken, and pig liver and chicken kidney were purified as described for rat kidney [23]
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