Biochemistry

Energy release does not exhaust the value of the tricarboxylic acid cycle. Its role is that in the aerobic oxidation of carbohydrates intermediate substances are formed, which are used for various processes of biosynthesis. Thus, a-ketoglutaric and oxalo-acetic acids can be converted into amino acids (glutamic and aspartic), necessary for the synthesis of proteins, nitrogenous bases, hormones, nucleotides. The inclusion of amino acids in the tricarboxylic acid cycle is presented in Figure 11.7. Figure 11.7 - Ways of inclusion of amino acids into the Krebs cycle The Krebs cycle supplies reductive equivalents to the chain of respiratory enzymes, where the flow of electrons and protons is associated with the formation of ATP. The cycle cannot proceed faster than the use of ATP allows. It is regulated by the type of feedback: ATP is inhibited and ADP is activated, which accumulates as ATP is utilized. Pentose carbohydrate oxidation cycle The idea of the existence in tissues of animals, plants, and microbes of a different mechanism for the oxidation of carbohydrates, which differs from that discussed above, was developed on the basis of the work of Warburg, Dickens, and V.A. Engelhardt, who showed the possibility of hexosomonophosphate oxidation in animal cells (for example, in erythrocytes) without preliminary splitting into 232