Induction of Aconitate Hydratase in Hepatocytes of Starving Rats

A. T. Eprintsev, E. V. Semenova, and V. N. Popov^*

School of Biology, Voronezh State University, Universitetskaya pl. 1, Voronezh, 394693 Russia; fax: (0-732) 78-9755; E-mail: bsbc366@main.vsu.ru

^* To whom correspondence should be addressed.

Received July 9, 2001; Revision received November 13, 2001

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Induction of the activity of aconitate hydratase (AH) was observed in rat hepatocytes under the conditions of food deprivation. The increase in AH activity after 4 days of starvation in the studied tissues was from 0.57 to 2.05 U/g crude liver weight. The induction of aconitase was associated both with the cytoplasmic and mitochondrial AH isoforms. The activities of cytosolic and mitochondrial AH isoforms in starving animals consisted of 83 and 17% of the total activity, respectively. The cytoplasmic and mitochondrial isoforms of the enzyme with specific activities 11.1 and 6.13 U/mg protein, respectively, were obtained by a five-step purification procedure that included fractionation with ammonium sulfate, ion-exchanging chromatography on DEAE-Toyopearl and gel filtration. The purified preparations of these AH isoforms were electrophoretically homogenous. The molecular weights of these isoforms were estimated and several kinetic and regulatory properties were studied.

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KEY WORDS: aconitate hydratase, food deprivation, hepatocytes, glyoxylate cycle, citric acid cycle, gluconeogenesis, purification, kinetic characteristics

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