The long flexible arm of phosphopantetheine allows its thiol to move from one active site to another within the complex. Fatty Acid Synthase complex is a dimer . The 2 copies of the enzyme are aligned antiparallel . The antiparallel arrangement favors inter-subunit transfer. The first 3 steps of the Fatty Acid Synthase reaction pathway are catalyzed by the catalytic domains listed in the diagram below.
Mammalian cells have limited capacity to introduce double bonds in fatty acids.
A fatty acid desaturase in endoplasmic reticulum membranes catalyzes a 4-electron reduction of O 2 to form 2 H 2 O . Two electrons are extracted from the fatty acid as the double bond is formed. O Copyright 1998-2001 by Joyce J. Diwan. All rights reserved.