First step occurs in cytosol - remainder of oxidation occurs in mitochondria. See Table 17.1. When unsaturated fatty acids are oxidized, the position of the cis double bond relative to the carbonyl carbon is important. If the cis-double bond lies between the b and g carbons, the bond is isomerized to a trans bond and oxidation continues. 2 acetyl CoA molecules condense to form acetoacetate which reacts further to form b -hydroxybutyrate, acetoacetate and acetone.
Process is catalyzed by fatty acid synthase complex.
Table 17.2 Anabolism of Triacylglycrols - via formation of glycerol phosphate. 17.21 showing carbons resulting from methyl and carbonyl carbons in cholesterol. Many of the cholesterol-lowering drugs inhibit this enzyme. Mevalonate is decarboxylated to form a derivative of isoprene. Five isoprene units are successively added to form squalene.