Most of the reducing equivalents utilized for synthesis of fatty acids can be generated from:
|A||The pentose phosphate pathway|
|C||The citric acid cycle|
|D||Mitochondrial malate dehydrogenase|
a. The sources of NADPH for synthesis of fatty acids are the pentose phosphate pathway and cytosolic malate formed during the transfer of acetyl groups to the cytosol as cit rate.
b. The enzyme citrate lyase splits citrate into acetyl CoA and oxaloacetate. The oxaloacetate is reduced to malate by NADH.
c. NADP linked malate enzyme catalyzes the oxidative decarboxylation of malate to pyruvate and carbon dioxide.
d. Thus, the diffusion of excess citrate from the mitochondria to the cytoplasm of cells not only provides acetyl CoA for synthesis of fatty acids but NADPH as well.
e. One NADPH is produced for each acetyl CoA produced. However, most of the NADPHs needed for syn thesis of fatty acids are derived from the pentose phosphate pathway.
f. For this reason, adipose tissue has an extremely active pentose phosphate pathway.