With the help of carnitine: fatty acyl-CoA transferase system on the mitochondrial inner membrane, fatty acyl-CoA enters the mitochondrial matrix, is degraded into acetyl-CoA by β-oxidation, and is completely oxidized after entering the tricarboxylic acid cycle.
The β -oxidation process includes four steps: dehydrogenation, hydration, re-dehydrogenation and thiolysis. FADH2, NADH, acetyl coenzyme A and fatty acyl coenzyme A with less than two carbon atoms are formed in each β -oxidation cycle.
In addition, in some tissues and cells, α -hydroxy fatty acids or CO2 and fatty acids with one less carbon atom are produced by α-oxidation. The corresponding dicarboxylic acids are formed by ω-oxidation.
Germinated oilseeds and some microorganisms have glyoxylic acid circulation pathway. Malic acid can be synthesized from acetyl coenzyme A produced by β -oxidation of fatty acids, which provides carbon source for gluconeogenesis and other biosynthesis. The two key enzymes in glyoxylic acid cycle are isocitrate lyase and malate synthase. The former catalyzes the cleavage of isocitrate into succinic acid and glyoxylic acid, while the latter catalyzes glyoxylic acid and acetyl coenzyme A to produce malic acid.
Human fat formation
Most of the fat ingested by human body is emulsified into small particles by bile. Lipases secreted by pancreas and small intestine hydrolyze fatty acids in fat into free fatty acids and monoglycerides (occasionally completely hydrolyzed into glycerol and fatty acids).
Hydrolyzed small molecules, such as glycerol, short-chain and medium-chain fatty acids, are absorbed by the small intestine and enter the blood. After monoglycerides and long-chain fatty acids are absorbed, triglycerides are first synthesized in small intestinal cells, and form chylomicrons with phospholipids, cholesterol and protein, which enter the blood circulation from the lymphatic system.
Refer to the above contents: Baidu Encyclopedia-Fat, Baidu Encyclopedia-Human Fat