Fatty acid synthetase is a multifunctional enzyme that catalyzes the de novo biosynthesis of long-chain saturated fatty acids starting from acetyl-CoA and malonyl-CoA in the presence of NADPH. This multifunctional protein contains 7 catalytic activities and a site for the binding of the prosthetic group 4'-phosphopantetheine of the acyl carrier protein ([ACP]) domain. acetyl-CoA + 2n H(+) + n malonyl-CoA + 2n NADPH = a long-chain fatty acid + n CO2 + (n+1) CoA + 2n NADP(+) acetyl-CoA + holo-[ACP] = acetyl-[ACP] + CoA holo-[ACP] + malonyl-CoA = CoA + malonyl-[ACP] a fatty acyl-[ACP] + H(+) + malonyl-[ACP] = a 3-oxoacyl-[ACP] + CO2 + holo-[ACP] a (3R)-hydroxyacyl-[ACP] + NADP(+) = a 3-oxoacyl-[ACP] + H(+) + NADPH a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O a 2,3-saturated acyl-[ACP] + NADP(+) = a (2E)-enoyl-[ACP] + H(+) + NADPH H2O + hexadecanoyl-[ACP] = H(+) + hexadecanoate + holo-[ACP] acetyl-[ACP] + H(+) + malonyl-[ACP] = 3-oxobutanoyl-[ACP] + CO2 + holo-[ACP] 3-oxobutanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxybutanoyl-[ACP] + NADP(+) (3R)-hydroxybutanoyl-[ACP] = (2E)-butenoyl-[ACP] + H2O (2E)-butenoyl-[ACP] + H(+) + NADPH = butanoyl-[ACP] + NADP(+) butanoyl-[ACP] + H(+) + malonyl-[ACP] = 3-oxohexanoyl-[ACP] + CO2 + holo-[ACP] 3-oxohexanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxyhexanoyl-[ACP] + NADP(+) (3R)-hydroxyhexanoyl-[ACP] = (2E)-hexenoyl-[ACP] + H2O (2E)-hexenoyl-[ACP] + H(+) + NADPH = hexanoyl-[ACP] + NADP(+) H(+) + hexanoyl-[ACP] + malonyl-[ACP] = 3-oxooctanoyl-[ACP] + CO2 + holo-[ACP] 3-oxooctanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxyoctanoyl-[ACP] + NADP(+) (3R)-hydroxyoctanoyl-[ACP] = (2E)-octenoyl-[ACP] + H2O (2E)-octenoyl-[ACP] + H(+) + NADPH = NADP(+) + octanoyl-[ACP] H(+) + malonyl-[ACP] + octanoyl-[ACP] = 3-oxodecanoyl-[ACP] + CO2 + holo-[ACP] 3-oxodecanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxydecanoyl-[ACP] + NADP(+) (3R)-hydroxydecanoyl-[ACP] = (2E)-decenoyl-[ACP] + H2O (2E)-decenoyl-[ACP] + H(+) + NADPH = decanoyl-[ACP] + NADP(+) decanoyl-[ACP] + H(+) + malonyl-[ACP] = 3-oxododecanoyl-[ACP] + CO2 + holo-[ACP] 3-oxododecanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxydodecanoyl-[ACP] + NADP(+) (3R)-hydroxydodecanoyl-[ACP] = (2E)-dodecenoyl-[ACP] + H2O (2E)-dodecenoyl-[ACP] + H(+) + NADPH = dodecanoyl-[ACP] + NADP(+) dodecanoyl-[ACP] + H(+) + malonyl-[ACP] = 3-oxotetradecanoyl-[ACP] + CO2 + holo-[ACP] 3-oxotetradecanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxytetradecanoyl-[ACP] + NADP(+) (3R)-hydroxytetradecanoyl-[ACP] = (2E)-tetradecenoyl-[ACP] + H2O (2E)-tetradecenoyl-[ACP] + H(+) + NADPH = NADP(+) + tetradecanoyl-[ACP] H(+) + malonyl-[ACP] + tetradecanoyl-[ACP] = 3-oxohexadecanoyl-[ACP] + CO2 + holo-[ACP] 3-oxohexadecanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxyhexadecanoyl-[ACP] + NADP(+) (3R)-hydroxyhexadecanoyl-[ACP] = (2E)-hexadecenoyl-[ACP] + H2O (2E)-hexadecenoyl-[ACP] + H(+) + NADPH = hexadecanoyl-[ACP] + NADP(+) H(+) + hexadecanoyl-[ACP] + malonyl-[ACP] = 3-oxooctadecanoyl-[ACP] + CO2 + holo-[ACP] 3-oxooctadecanoyl-[ACP] + H(+) + NADPH = (3R)-hydroxyoctadecanoyl-[ACP] + NADP(+) (3R)-hydroxyoctadecanoyl-[ACP] = (2E)-octadecenoyl-[ACP] + H2O (2E)-octadecenoyl-[ACP] + H(+) + NADPH = NADP(+) + octadecanoyl-[ACP] H2O + tetradecanoyl-[ACP] = H(+) + holo-[ACP] + tetradecanoate Lipid metabolism; fatty acid biosynthesis. Homodimer which is arranged in a head to tail fashion (By similarity). Interacts with CEACAM1; this interaction is insulin and phosphorylation-dependent; reduces fatty-acid synthase activity (By similarity). Up-regulated by endocannabinoid anandamide/AEA. S-nitrosylation of Fatty acid synthase at cysteine residues Cys-1464 or Cys-2084 is important for the enzyme dimerization. In adipocytes, S-nitrosylation of Fatty acid synthase occurs under physiological conditions and gradually increases during adipogenesis.