The biosynthesis of Palmitic Acid Deutsch is carried out in chloroplasts and protoplasts in plants, and saturated fatty acids of 4 to 16 carbons and above are synthesized. Animals are carried out in the cytosol, only 16-carbon saturated fatty acids are synthesized, and fatty acids longer than 16 carbons are synthesized in the endoplasmic reticulum or mitochondria. In terms of the synthesis process of 16-carbon saturated fatty acids in the cytosol, there are similarities with the β-oxidation process, but the synthesis process is not a simple reversal of the β-oxidation process.
The similarities and differences between Palmitic Acid Deutsch synthesis and fatty acid β-oxidation can be summarized as follows:
①The two pathways take place in different places, β-oxidation is mainly carried out in mitochondria, and de novo synthesis of saturated fatty acids is carried out in cytosol;
② Both pathways have an intermediate connected to the carrier, fatty acid synthesis is ACP, β-oxidation is CoA;
③ There are 4 steps in both pathways, fatty acid synthesis is condensation, reduction, dehydration and reduction, fatty acid β-oxidation is dehydrogenation, water addition, then dehydrogenation and thiolysis. Although chemically the two are inverse reactions to each other. But they have different reaction processes and use different cofactors;
④ Both pathways have raw material transport mechanisms. In Palmitic Acid Deutsch synthesis, there is a tricarboxylic acid transport mechanism that transports acetyl CoA from mitochondria to the cytoplasm. In degradation, there is a carnitine carrier system that transports fatty acyl CoA from the cytoplasm to the cytoplasm. mitochondria;
⑤ Both pathways are characterized by the successive changes of the fatty acid chain. In the fatty acid synthesis, the fatty acid chain obtains a 2-carbon unit and successfully extends, and in the degradation, the 2-carbon unit in the form of acetyl CoA leaves to realize the fatty acid. shortening of the chain;
⑥ When fatty acid is synthesized, it starts from the methyl end of the molecule to the carboxyl end, and the degradation is in the opposite direction, and the departure of the carboxyl group is the first step.
⑦Hydroxyester intermediate is D-configuration in fatty acid synthesis, but L-configuration in degradation;
⑧ Fatty acid synthesis is composed of the reduction pathway, which requires the participation of NADPH, and fatty acid decomposition is composed of the oxidative pathway, which requires the participation of FAD and NAD+;
⑨ In animals, Palmitic Acid Deutsch synthase is a multifunctional enzyme composed of a polypeptide chain, and the decomposition of fatty acids is catalyzed by a variety of enzymes.
⑩ β-oxidation is a process that generates a large amount of energy in addition to the energy consumption in the initial activation. De novo synthesis of saturated fatty acids is an energy-intensive process.
The above are the important similarities and differences between fatty acid synthesis in cytosol and β-oxidation in mitochondria. In mitochondria, Palmitic Acid Deutsch synthesis is the inverse of β-oxidation