Induction of glyoxylate cycle enzymes in rat liver upon food starvation |
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Authors: | Vasily N Popov Abir U Igamberdiev Claus Schnarrenberger Sergei V Volvenkin |
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Institution: | aDepartment of Plant Physiology and Biochemistry, Voronezh State University, Voronezh 394693, Russian Federation;bInstitute for Plant Physiology and Microbiology, Freie Universität Berlin, Königin-Luise-Str. 12-16a, D-14195 Berlin, Germany |
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Abstract: | The key enzymes of the glyoxylate cycle, isocitrate lyase and malate synthase, have been detected in liver of foodstarved rats. Activities became measurable 3 days and peaked 5 days after the beginning of starvation. Both enzymes were found in the peroxisomal cell fraction after organelle fractionation by isopycnic centrifugation. Isocitrate lyase was purified 112-fold by ammonium sulfate precipitation, and chromotography on DEAE-cellulose and Toyopearl HW-65. The specific activity of the purified enzyme was 9.0 units per mg protein. The Km(isocitrate) was 68 μM and the pH optimum was at pH 7.4. Malate synthase was enriched 4-fold by ammonium sulfate precipitation. The enzyme had a Km(acetyl-CoA) of 0.2 μM, a Km(glyoxylate) of 3 mM and a pH optimum of 7.6. |
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Keywords: | Isocitrate lyase Malate synthase Rat liver Glyoxylate cycle |
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