Citrate synthase of Tetrahymena pyriformis: evolutionary and regulatory aspects

Archives of Biochemistry and Biophysics
I FabregatA Machado

Abstract

Citrate synthase (EC 4.1.3.7) from Tetrahymena pyriformis has been purified 185-fold. The molecular weight of the native enzyme was determined to be 120,000. The enzyme is labile at low ionic strength, but can be stabilized by KCl and glycerol. It is activated by KCl at low (below 60 mM) or high concentrations, and inhibited by divalent cations (Mn2+, Mg2+, Ca2+). The Michaelis constants are 0.1 mM for oxalacetate and 0.01 mM for acetyl-CoA. The kinetics with oxalacetate exhibit negative cooperativity, with a nH = 0.66. Among the metabolites tested, only ATP and GTP can inhibit the enzyme but Mg2+ relieves the ATP inhibition. Incubation with sulfhydryl reagents (DTNB) in the absence of its substrates results in a rapid inactivation of the enzyme. It is concluded that Tetrahymena citrate synthase is closer to the enzyme from Gram-positive bacteria than to those of eucaryotes.

References

Jan 1, 1976·Current Topics in Cellular Regulation·P D Weitzman, M J Danson
Oct 7, 1977·Molecular and Cellular Biochemistry·P Vidal, A Machado
Dec 1, 1978·Archives of Biochemistry and Biophysics·M A MatlibP A Srere
Nov 1, 1979·European Journal of Biochemistry·M J DansonP D Weitzman
Jul 20, 1968·Nature·P D Weitzman, D Jones
Jan 7, 1969·Biochimica Et Biophysica Acta·P D Weitzman, P Dunmore
Oct 17, 1966·Biochimica Et Biophysica Acta·P D Weitzman
Mar 1, 1970·Archives of Biochemistry and Biophysics·J J Blum
Jan 1, 1972·Current Topics in Cellular Regulation·P A Srere
Aug 18, 1972·European Journal of Biochemistry·A Måhlén
Feb 1, 1970·Proceedings of the Society for Experimental Biology and Medicine·M E Plaut, J K Goldman
Jan 22, 1971·Life Sciences. Pt. 2: Biochemistry, General and Molecular Biology·L L Poulsen, I V Sarkissian
Jul 30, 1969·Biochimica Et Biophysica Acta·V R Flechtner, R S Hanson
Sep 1, 1980·Canadian Journal of Biochemistry·D Morse, H W Duckworth
Jan 4, 1965·Biochemical and Biophysical Research Communications·P A SRERE
Jul 13, 2013·Surgical Endoscopy·Michael V DoWilliam S Richardson

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