**4. Conclusions**

Enzyme inhibitors and activators are a number of various chemical compounds that can slow down (or even stop) and activate enzymes, natural protein catalysts. They include inorganic compounds (often anions), different organic compounds (mainly containing reactive groups that can modify amino acids of protein), natural proteins, lipids, and carbohydrates. Mechanism of inhibitor and activator action on the enzyme activity includes a step of their binding to the enzyme, after which a step of the change of enzyme conformation often follows.

Inhibitors are a good tool for study of enzyme reaction mechanisms. Many natural inhibitors especially obtained from plants and invertebrates often imitate natural proteins or some of their motifs that participate in the protein-protein interactions in the cell that are important for metabolic regulation. Among enzyme activators and inhibitors, one can highlight a group of allosteric modulators that participate in feedback regulation of metabolic pathways. And finally, we should note a practical significance of enzyme inhibitors that are a base for the design of different classes of pharmaceutical drugs, pesticides, and insecticides.
