Acetyl-CoA carboxylase (ACC) is the enzyme that catalyzes the chemical addition of carbon dioxide to acetyl-CoA, malonyl-CoA which occurs. This reaction is the first and rate-limiting step in fatty acid synthesis of all living beings. In detail, the reaction takes place in two steps catalyzed only in eukaryotes and some bacteria of the same enzyme; with all other two enzymes are required for this. Man has two isozymes ACC1 ( cytosolic ) and ACC2 ( mitochondrial ), which are encoded by the genes ACACA and ACACB. Mutations in ACACA gene can lead to enzyme defects and for this rare genetic disorder of the ACC deficiency with severe brain damage and muscle weakness.

A study by polymorphisms in ACACB gene could be responsible for metabolic syndrome. In addition to their regulation by transcription factors ( SREBP1 ) or phosphorylation of AMPK is the ACC activity controlled by the degree of Enzympolymerisation, which is influenced by the MIG12 protein.

Catalyzed reaction

Taking place overall reaction is:

In detail, there are two reactions in sequence:

First carbonate is added to the biotin moiety, which consumes a molecule of ATP.

Then carbonate is transferred to acetyl -CoA. Both reactions take place in animals of the same enzyme that carries both the two catalytic domains necessary, as is also used as a biotin carrier protein. For all other organisms, these binding sites are located on multiple individual proteins, which in turn form a protein complex.