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Purification and Properties of Succinyl‐CoA:3‐Oxo‐Acid CoA‐Transferase from Rat Brain
Author(s) -
Russell Joseph J.,
Patel Mulchand S.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb07924.x
Subject(s) - transferase , sephadex , enzyme , biochemistry , polyacrylamide gel electrophoresis , coenzyme a , ketone bodies , chemistry , gel electrophoresis , chromatography , substrate (aquarium) , sodium dodecyl sulfate , specific activity , metabolism , biology , reductase , ecology
Rat brain succinyl‐CoA:3‐oxo‐acid CoA‐transferase (3‐Oxo‐acid CoA‐transferase, EC 2.8.3.5), the first committed enzyme in the oxidation of ketone bodies in mitochondria, was purified to apparent homogeneity as judged by polyacrylamide gel electrophoresis. The enzyme has an apparent molecular weight of 90,000 as determined by (3‐150 Sephadex chromatography, and an apparent subunit molecular weight of 53,000 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The specific activity of the purified enzyme was approximately 161 μmol/min/mg of protein. Initial velocity studies of the forward reaction (acetoacetate → acetoacetyl‐CoA) are consistent with a “ping pong” mechanism. Substrate inhibition appears above approximately 1 m M acetoacetate. Apparent K m , values were 70 μM for acetoacetate and 156 μ M for succinyl‐CoA (the forward reaction), and 59 μ M for acetoacetyl‐CoA and 25 m M for succinate (the reverse reaction). These values are markedly different from those reported for this enzyme from pig heart.