PMID: 1256Nov 15, 1975

On the mechanism of ketogenesis and its control. Purification, kinetic mechanism and regulation of different forms of mitochondrial acetoacetyl-CoA thiolases from ox liver

European Journal of Biochemistry
W HuthW Seubert

Abstract

1. Two mitochondrial forms of acetoacetyl-CoA thiolases designated as enzyme A and enzyme B were crystallized from ox liver. They could be shown to be homogenous by polyacrylamide gel electrophoresis. 2. In direction of acetoacetyl-CoA cleavage enzyme A shows a double competitive substrate inhibition when acetoacetyl-CoA is varied at different fixed CoA concentrations. With enzyme B a parallel kinetic pattern is obtained when acetoacetyl-CoA is varied at different fixed CoA concentrations. In direction of acetoacetyl-CoA synthesis both enzymes show linear reciprocal plots of initial velocities against acetyl-CoA concentrations in absence of CoA. These initial velocity kinetics in the forward and in the reverse direction are in accordance with a ping-pong mechanism of reaction for both enzymes involving an acetyl-S-enzyme as intermediate. 3. Under saturating concentrations of substrate, the ratios of acetoacetyl-CoA synthesis/aceto-acetyl-CoA cleavage is 0.31 for enzyme A and 0.08 for enzyme B. The maximum velocity in direction of acetoacetyl-CoA synthesis of enzymes A and B are 0.43 mumol X min-1 X unit thiolase-1 and 0.10 mumol X min-1 X unit thiolase-1, respectively. 4. Both enzymes show nearly the same affinity for acetyl-Co...Continue Reading

References

Feb 27, 1974·Biochemical and Biophysical Research Communications·W HuthW Seubert
Jan 1, 1966·Advances in Enzyme Regulation·H A Krebs
Feb 1, 1972·Canadian Journal of Biochemistry·L P Lee, I B Fritz
Jan 31, 1972·Biochemical and Biophysical Research Communications·B Middleton
Sep 1, 1970·The Biochemical Journal·H A Krebs, R Hems
Nov 1, 1968·European Journal of Biochemistry·U GehringF Lynen
May 1, 1969·The Biochemical Journal·H A KrebsR A Freedland
May 1, 1953·Biochimica Et Biophysica Acta·G W BROWN, I L CHAIKOFF
Jan 1, 1967·Annual Review of Biochemistry·W W Cleland

Citations

Oct 1, 1981·European Journal of Biochemistry·L A MenahanH M Miziorko
Mar 15, 1988·European Journal of Biochemistry·W HuthU Möller
Jun 1, 1983·The Proceedings of the Nutrition Society·V A Zammit
Aug 1, 1979·Metabolism: Clinical and Experimental·D S SchadeR P Eaton
Dec 17, 2016·International Journal of Molecular Sciences·Maja GrabackaKrzysztof Reiss
Apr 30, 1978·Archives of Biochemistry and Biophysics·M S Owens, R E Barden
Feb 1, 1980·European Journal of Biochemistry·S MiyazawaT Hashimoto
May 12, 2000·European Journal of Biochemistry·V D AntonenkovG P Mannaerts
Mar 25, 2005·Molecular and Cellular Biochemistry·Anastasia A PantazakiDimitrios A Kyriakidis

Related Concepts

Acetyl-CoA C-Acetyltransferase
Acetyltransferase
Bos indicus
CoASH
Polymorphism, Crystallization
Hydrogen-Ion Concentration
Alloenzymes
Mitochondria, Liver
Plasma Protein Binding Capacity

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