Biochemistry

Figure 3.1 - Structure of enzymes The substrate-binding center is a portion of the enzyme molecule that directly interacts with the substrate. In proteinase enzymes, the substrate-binding center may coincide with the active center. The allosteric center is a part of an enzyme molecule that is not identical in structure to the substrate (from the Greek alios - different, other). It interacts with certain low molecular weight substances, such as hormones. The addition of such substances to the allosteric center leads to a change in the tertiary structure of the protein molecule. This, in turn, changes the configuration of the substrate-binding center and is accompanied by a change (increase or decrease) in the catalytic activity of the enzyme. 3.3 PROPERTIES OF ENZYMES All enzymes are high molecular weight biopolymers. The protein nature of enzymes determines a number of their properties that differ from those of inorganic catalysts. The most important feature of the action of enzymes is their specificity, which determines the selectivity of their action. It is enough to change the spatial arrangement of the substrate atoms so that the enzyme does not affect it. An enzyme can catalyze one or a group of reactions that are similar in nature. Due to their specificity, only a few are selected from the range of thermodynamically possible chemical reactions, and therefore not only accelerate 83