Induction of glyoxylate cycle enzymes in rat liver upon food starvation.
The key enzymes of the glyoxylate cycle, isocitrate lyase and malate synthase, have been detected in liver of food-starved 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 K(m)(isocitrate) was 68 microM and the pH optimum was at pH 7.4. Malate synthase was enriched 4-fold by ammonium sulfate precipitation. The enzyme had a K(m)(acetyl-CoA) of 0.2 microM, a K(m)(glyoxylate) of 3 mM and a pH optimum of 7.6.
Popov
V N
VN
Department of Plant Physiology and Biochemistry, Voronezh State University, Russian Federation.
Igamberdiev
A U
AU
Schnarrenberger
C
C
Volvenkin
S V
SV
D000818:Animals; D002499:Centrifugation, Density Gradient; D004790:Enzyme Induction; D006038:Glyoxylates / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007522:Isocitrate Lyase / Q000096:biosynthesis* / Q000302:isolation & purification; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008292:Malate Synthase / Q000096:biosynthesis* / Q000302:isolation & purification; D008830:Microbodies / Q000201:enzymology; D051381:Rats; D013217:Starvation / Q000201:enzymology*
D006038:Glyoxylates; D008292:Malate Synthase; D007522:Isocitrate Lyase; C031150:glyoxylic acid