<p>Beta-ketoacyl-ACP synthase <db_xref db="EC" dbkey="2.3.1.41"/> (KAS) [<cite idref="PUB00000791"/>] is the enzyme that catalyzesthe condensation of malonyl-ACP with the growing fatty acid chain. It is found as a componentof a number of enzymatic systems, including fatty acid synthetase (FAS), which catalyzes theformation of long-chain fatty acids from acetyl-CoA, malonyl-CoA and NADPH; the multi-functional 6-methysalicylic acid synthase (MSAS) from <taxon tax_id="5078">Penicillium patulum</taxon> [<cite idref="PUB00001385"/>], which isinvolved in the biosynthesis of a polyketide antibiotic; polyketide antibiotic synthase enzymesystems; <taxon tax_id="162425">Emericella nidulans</taxon> multifunctional protein Wa, which is involved in the biosynthesisof conidial green pigment; Rhizobium nodulation protein nodE, which probably acts as a beta-ketoacyl synthase in the synthesis of the nodulation Nod factor fatty acyl chain; and yeastmitochondrial protein CEM1. The condensation reaction is a two step process, first the acylcomponent of an activated acyl primer is transferred to a cysteine residue of the enzyme andis then condensed with an activated malonyl donor with the concomitant release of carbondioxide.</p><p>Beta-ketoacyl synthase also contains most of the structures involved in dimer formation.</p><p>This entry represents the active site of beta-ketoacyl-ACP synthases [<cite idref="PUB00019762"/>].</p> Beta-ketoacyl synthase, active site