Inactivation of aspartate aminotransferase during transamination with chloropyruvate. Evidence against modification of Cys390 in cytosolic isoenzyme. |
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Authors: | A M Osman T Yamano |
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Institution: | Department of Biochemistry Osaka University Medical School Joancho, Kita-ku, Osaka 530 Japan;Department of Biochemistry Kumamoto University Medical School Honjo, Kumamoto 860 Japan |
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Abstract: | Both the cytosolic and mitochondrial isoenzyme of aspartate aminotransferase from pig heart were inactivated during transamination with chloropyruvate. Inactivation occurred with L-alanine as the amino group donor in the presence of potassium formate. When L-glutamate or L-aspartate was employed as the amino group donor in the transamination reaction with chloropyruvate, no inactivation occurred. This is in contrast to the case of inactivation by bromopyruvate (Okamoto, M. &; Morino, Y. (1973) J. Biol. Chem. , 82–90) where these natural dicarboxylic amino acid substrates were effective in the transamination reaction leading to syncatalytic inactivation (Birchmeier, W. &; Christen, P. (1974) J. Biol. Chem. , 6311–6315). The Cys390 in the cytosolic isoenzyme which was modified in the syncatalytic inactivation was not modified under the present condition for inactivation with either chloropyruvate or bromopyruvate. |
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Keywords: | Cys cysteinyl residue EDTA ethylenediaminetetraacetate |
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