In enzymology, a mycocerosate synthase () is an enzyme that catalyzes the chemical reaction
The 4 substrates of this enzyme are acyl-CoA, methylmalonyl-CoA, NADPH, and H<sup>+</sup>, whereas its 4 products are multi-methyl-branched acyl-[mycocerosate synthase], CoA, CO<sub>2</sub>, and NADP<sup>+</sup>.
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:methylmalonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing). This enzyme is also called mycocerosic acid synthase.