The kinetic properties of citrate synthase from rat liver mitochondria.
1. Citrate synthase (EC 4.1.3.7) was purified 750-fold from rat liver. 2. Measurements of the Michaelis constants for the substrates of citrate synthase gave values of 16mum for acetyl-CoA and 2mum for oxaloacetate. Each value is independent of the concentration of the other substrate. 3. The inhibition of citrate synthase by ATP, ADP and AMP is competitive with respect to acetyl-CoA. With respect to oxaloacetate the inhibition by AMP is competitive, but the inhibition by ADP and ATP is mixed, being partially competitive. 4. At low concentrations of both substrates the inhibition by ATP is sigmoidal and a Hill plot exhibits a slope of 2.5. 5. The pH optimum of the enzyme is 8.7, and is not significantly affected by ATP. 6. Mg(2+) inhibits citrate synthase slightly, but relieves the inhibition caused by ATP in a complex manner. 7. At constant total adenine nucleotide concentration made up of various proportions of ATP, ADP and AMP, the activity of citrate synthase is governed by the concentration of the sum of the energy-rich phosphate bonds of ADP and ATP. 8. The sedimentation coefficient of the enzyme, as measured by activity sedimentation, is 6.3s, equivalent to molecular weight 95000.
D000227:Adenine Nucleotides / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002951:Citrates / Q000096:biosynthesis*; D003065:Coenzyme A / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008190:Lyases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000201:enzymology*; D008970:Molecular Weight; D010071:Oxaloacetates / Q000378:metabolism; D051381:Rats; D014461:Ultracentrifugation
D000227:Adenine Nucleotides; D002951:Citrates; D010071:Oxaloacetates; D000255:Adenosine Triphosphate; D008190:Lyases; D008274:Magnesium; D003065:Coenzyme A
Biochim Biophys Acta. 1967 May 16;139(1):195-8
4382275
Biochim Biophys Acta. 1963 Jan 8;67:104-37
14021667
Biochem J. 1961 Aug;80:324-32
13785321
Biochem Z. 1962;335:426-39
13909144
J Biol Chem. 1961 Oct;236:2560-5
14458636
Biochim Biophys Acta. 1966 Oct 17;128(1):190-2
5972360
Biochem J. 1967 May;103(2):514-27
4291787
Biochem J. 1968 Dec;110(4):747-8
4303066
Biochim Biophys Acta. 1967 Jul 11;139(2):526-8
4291928
Biochim Biophys Acta. 1968 Jan 8;151(1):225-35
4867623
J Biol Chem. 1967 Jul 10;242(13):3239-41
6027798
Biochim Biophys Acta. 1963 Jul 9;73:519-22
14068532
J Biol Chem. 1951 Dec;193(2):691-702
14907759
J Biol Chem. 1966 Aug 10;241(15):3571-4
4380667
Biochem Biophys Res Commun. 1967 Jun 23;27(6):686-92
4964598
Biochemistry. 1964 Jan;3:18-26
14114498
Biochim Biophys Acta. 1966 Oct 17;128(1):213-5
4382043
Nature. 1963 May 4;198:463-5
14021666
Biochem Biophys Res Commun. 1965 Sep 8;20(5):661-5
5861846
Cold Spring Harb Symp Quant Biol. 1961;26:313-8
13878122
Cold Spring Harb Symp Quant Biol. 1961;26:389-401
14475415
Biochim Biophys Acta. 1957 Sep;25(3):575-8
13479429
Biochem Soc Symp. 1968;27:11-21
4319082
Biochem Soc Symp. 1968;27:41-60
4319084
Biochem Biophys Res Commun. 1966 Jan 4;22(1):89-93
5937344
Biopolymers. 1967 Feb;5(2):203-25
6040718
Proc Natl Acad Sci U S A. 1966 Aug;56(2):680-5
5229985
Biochem Soc Symp. 1968;27:23-40
5759705
Biochem J. 1965 Nov;97(2):587-94
16749169
J Biol Chem. 1961 Oct;236:2557-9
13915993
Nature. 1962 Jul 28;195:381-3
13896984