V. De novo Synthesis of Fatty Acids
Enzymes and Isolated Reactions: Characteristics of Fatty Acyl Synthase
Fatty acyl synthase has three important characteristics :
- It is essential, but not rate-limiting, for fatty acid
synthesis. It is not subject to short term control.
- ACP and the catalytic activities are on a single contiguous
protein (257 kDa).
- In animals the synthase is active only as a dimer. The
malonyl/acetyl transferase, condensing enzyme and
dehydratase activities from the first subunit and all the other
activities from the second subunit form one functional unit. A
second functional unit forms from the remainder of the two
In contrast, bacterial activities are all on separate enzymes.
Interestingly, the enoyl reductase of Mycobacterium tuberculosis is
the target of isoniazid and other major antituberculosis drugs.