Citrate synthase

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Citrate synthase
Identifiers
Symbol(s)	CS
Entrez	1431
OMIM	118950
RefSeq	[1]
UniProt	O75390
Other data
EC number	2.3.3.1
Locus	Chr. 12 p11-qter

In Krebs cycle(aka the citric acid cycle). , the enzyme Citrate synthase (E.C. 2.3.3.1 [previously 4.1.3.7]) is a pace-maker enzyme as it controls the first committed step of the cycle.

Citrate synthase is localized within cells in the mitochondrial matrix but is nuclear encoded. It is synthesized on cytoplasmic ribosomes and then transported into the mitochondrial matrix. Citrate synthase is commonly used as a quantitative enzyme marker for the content of intact mitochondria.

Citrate synthase catalyzes the condensation reaction of a two carbon molecule, acetyl coenzyme A (acetyl CoA) with a four carbon molecules oxaloacetate to form citrate (6 carbons). Oxaloacetate will be regenerated after the citrate is oxidative decarboxylated to be four carbon molecules in Kerbs Cycle.

Acetyl-CoA + oxaloacetate + H2O → citrate + CoA-SH

The enzyme is inhibited by high ratio of ATP:ADP, Acetyl CoA:CoA and NADH:NAD as high concentration of ATP,Acetyl CoA and NADH show that the energy supply is high for the cell.