Fatty acid synthesis: Difference between revisions
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'''Straight-chain fatty acids''' | '''Straight-chain fatty acids''' | ||
Straight-chain fatty acid synthesis occurs via the six recurring reactions shown below, until the 16-carbon palmitic acid is produced. The fatty acids are synthesized in microorganisms and list the enzymes found in ''Escherichia coli''. Fatty acid synthesis is performed by fatty acid synthase II (FASII), which in general contain multiple enzymes that act as one complex. FASII is present in prokaryotes, plants, fungi, and parasites, as well as in mitochondria. | Straight-chain fatty acid synthesis occurs via the six recurring reactions shown below, until the 16-carbon <scene name='92/928693/Cv/2'>palmitic acid</scene> is produced. The fatty acids are synthesized in microorganisms and list the enzymes found in ''Escherichia coli''. Fatty acid synthesis is performed by fatty acid synthase II (FASII), which in general contain multiple enzymes that act as one complex. FASII is present in prokaryotes, plants, fungi, and parasites, as well as in mitochondria. | ||
Most of the acetyl-CoA which is converted into fatty acids is derived from carbohydrates via the [[glycolytic pathway]]. '''Pyruvate decarboxylation or pyruvate oxidation''', also known as the link reaction (or oxidative decarboxylation of pyruvate), is the conversion of <scene name='39/392339/Cv1/11'>pyruvate</scene> into <scene name='43/430893/Cv/2'>Acetyl-CoA</scene> by the enzyme complex pyruvate dehydrogenase complex (see [[Pyruvate dehydrogenase]]). | |||
''Step 1 Acetyl-CoA:ACP transacylase; (acyl-carrier-protein) S-acetyltransferase; EC 2.3.1.38'' | ''Step 1 Acetyl-CoA:ACP transacylase; (acyl-carrier-protein) S-acetyltransferase; EC 2.3.1.38'' | ||
*[[Acyl carrier protein]] (ACP). | *[[Acyl carrier protein]] (ACP). | ||
Acetyl-CoA + [acyl-carrier-protein] ⇌ CoA + acetyl-[acyl-carrier-protein] | <scene name='43/430893/Cv/2'>Acetyl-CoA</scene> + [acyl-carrier-protein] ⇌ CoA + acetyl-[acyl-carrier-protein] | ||
''Step 2 Malonyl CoA:ACP transacylase; (acyl-carrier-protein) S-malonyltransferase; EC 2.3.1.39'' | ''Step 2 Malonyl CoA:ACP transacylase; (acyl-carrier-protein) S-malonyltransferase; EC 2.3.1.39'' | ||
malonyl-CoA + acyl carrier protein ⇌ CoA + malonyl-[acyl-carrier-protein] | <scene name='92/928693/Cv/1'>malonyl-CoA</scene> + acyl carrier protein ⇌ CoA + malonyl-[acyl-carrier-protein] | ||
''Step 3 3-ketoacyl-ACP synthase; Beta-ketoacyl-ACP synthase I; Acyl carrier protein synthase; EC 2.3.1.41'' | |||
Acyl-acyl-carrier-protein + malonyl-acyl-carrier-protein ⇌ 3-oxoacyl-acyl-carrier-protein + CO2 + acyl-carrier-protein | |||
*[[Acyl carrier protein synthase]] | |||
''Step 4 3-ketoacyl-ACP reductase; 3-oxoacyl-[acyl-carrier-protein] reductase; EC 1.1.1.100'' | |||
3-oxoacyl-[acyl-carrier-protein](ACP) + NADPH + H+ ⇌ (3R)-3-hydroxyacyl-[acyl-carrier-protein](ACP) + NADP+ | |||
*[[1i01]] | |||
''Step 5 3-Hydroxyacyl ACP dehydrase; Beta-hydroxyacyl-acyl carrier protein dehydratase'' | |||
*[[Beta-hydroxyacyl-acyl carrier protein dehydratase]] | |||
''Step 6 Enoyl-ACP reductase; EC 1.3.1.9'' | |||
*[[Enoyl-Acyl-Carrier Protein Reductase]] | |||
'''Conversion of carbohydrates into fatty acids''' | |||
In humans, fatty acids are formed from carbohydrates predominantly in the liver and adipose tissue, as well as in the mammary glands during lactation. The pyruvate produced by glycolysis is an important intermediary in the conversion of carbohydrates into fatty acids (see [[Lipids: structure and classification]]) and cholesterol. | |||
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
<references/> | <references/> | ||