Biochemistry

one, but several enzymes, which is associated with the formation of various intermediate compounds, which can also play the role of inducers. An increase in the activity of enzymes under the influence of certain inductors enhances the biosynthesis of new enzymes or changes the activity of existing ones, and under the influence of damaging factors (for example, ionizing radiation), a qualitative change in the catalytic properties of enzymes can occur. The most important type of regulation of enzyme activity in cells is the intensity of their synthesis that depends on the activity of the genetic apparatus. Finally, the biochemical and physiological mechanisms of regulation of enzyme activity is a change in their activity, mainly through allosteric centers. This process occurs under the influence of specific substances on enzymes, the function of which is to coordinate metabolic reactions in cells and adapt them to changing conditions of the internal and external environment. Such substances include hormones produced by the endocrine glands, and tissue hormones (histohormones), which are formed in cells and do not have specialized hormonal function. So, the adrenaline hormone is synthesized in the adrenal medulla, which activates an enzyme that catalyzes the breakdown of glycogen (found in the liver and muscles) through a chain of biochemical reactions. The intensity of the formation of certain hormones is regulated by the nervous system. Thus, the body carries out step-by-step control over the action of enzymes that directly trigger biochemical processes. One of the ways to ensure the reliability of chemical reactions in cells is the formation of isoenzymes (isoenzymes), which catalyze the same reactions, but differ in sensitivity to activators and inhibitors. Isozymes have a different structure, which causes a difference in their properties. Therefore, if the conditions in the cells change, then isoenzymes can “ insure ” the implementation of important biochemical processes. The ratio of different isoenzymes can characterize the presence of metabolic disorders in the cells; it is widely used for diagnosis in medical practice. As noted earlier, whole multienzyme systems function in cells. In such systems, the final product of successive enzymatic transformations inhibits the first enzyme (by binding to its allosteric center), as a result of which the speed of the entire enzymatic process is determined by the constant concentration of the final product. The first enzyme of such a multienzyme system is called a regulatory or allosteric enzyme, and the inhibitory one is called an effector or modulator. The regulatory enzyme can be affected by both a negative modulator that causes its inhibition, and a positive one that increases the activity of the enzyme. The source substrate can act as a positive modulator. Thus, the substrate, degradation products, isoforms, enzymes that requiring activators have a regulatory effect on the activity of enzymes. The coordination of 93