Inhibitors

in biology, natural and synthetic substances that restrain the activity of enzymes in the living organism as well as in acellular systems; they are differentiated according to their mode of action, specificity, and other properties. Metabolic products may function in the body as natural inhibitors of enzymes. By analogy with technology, such inhibition is called feedback inhibition, since the end product of any biosynthetic process specifically inhibits one of its first stages.

Inhibition is effected either at the genetic level (the inhibitor, in this case called a repressor, retards the biosynthesis of one of the enzymes active at the start of the biosynthetic chain) or the kinetic level (the inhibitor, called a retroinhibitor, lowers the activity of that enzyme). Retroinhibition is a frequent case of so-called allosteric control of enzyme activity.

Inhibitors are widely used to study the mechanisms of the catalytic action of enzymes, to establish the nature of functional groups of proteins, and to elucidate the role of various enzyme processes in metabolism. Inhibitors have great practical significance. Thus, the use of toxic chemicals to control harmful insects and weeds is the result of their ability to inhibit processes vitally important to those organisms. The action of certain pharmacological agents and medicines is also based on the inhibition of enzyme reactions. In a broader sense, the term “inhibitors” is used to designate substances that inhibit any complex biological process (for example, growth inhibitors of plants).