Biochemistry

During the oxidation of palmitic acid seven cycles of 0 -oxidation - (16/2 - l)occurs , which leads to the formation of 35 ATP molecules. As a result of the 0- oxidation of this acid, eight acetyl-CoA (16/2) molecules are formed, each of which, oxidizing in the tricarboxylic acid cycle, produces 12 ATP molecules, i.e. forms 96 ATP molecules. Thus, the total energy output during the oxidation of one palmitic acid molecule will be: 35 + 96 = 131 ATP molecules. Since one molecule of ATP was expended on activating higher fatty acid at the beginning of the process, therefore, the energy output will be 130 ATP molecules. About 45% of the total potential energy of palmitic acid during its oxidation in the body can be used for the resynthesis of ATP, the rest is utilized in the form of heat. Oxidation of unsaturated fatty acids is the same as that of saturated, but has its own characteristics, due to the position of double bonds. Prior to the onset of 0- oxidation, the double bond in the fatty acid molecule moves from 3-4 to 2-3 and the configuration of thedouble bond changes from cis to trcms-position. Most natural lipids contain fatty acids with an even number of carbon atoms. However, fatty acids with an odd number of carbon atoms are found in the lipids of plants and some marine organisms. They also undergo 0-oxidation, which results in acetyl -CoA and propionyl-CoA. The latter is converted to succinyl-CoA - a metabolite of the Krebs cycle. The process of p-oxidation of higher fatty acids with the participation of HS coenzyme A is more active in the liver, fatty tissue, cardiac and skeletal muscles, and weaker in the kidneys, pancreas and other organs. Metabolism of ketonic (acetonic) bodies Ketonic (acetonic) bodies are acetoacetic acid (acetoacetate) CH 3 - CO - CH 2 - COOH, p-hydroxybutyric acid (0-oxybutyrate) CH 3 - CHOH-CH 2 - COOH and acetone CH 3 - CO - CH 3 . They are formed in the liver from acetyl-CoA. In the first stage of this process, acetoacetyl-CoA is formed from two acetyl-CoA molecules. 0 О 0 0 // // II n R-CH 2 -C + СНз-С CH3-C-CH2-C 4-HSCoA \ \ • HSC oa \ SCoA SCoA SCoA Acyl-CoA Acetyl-CoA Acetoacyl-CoA Then acetoacetyl-CoA interacts with another acetyl-CoA molecule. 198