[Stereochemical enhancement of specificity in biological recognition systems]

Specificity of the reaction of equilibrium association as a model of recognition process has been analysed. It has been shown that subdividing the centres of recognition into two uncoupled groups may lead to the effect of stereochemical enhancement of specificity, i. e. an increase of the fraction of the correct complex. If the second group of centers is unspecific, then a compensation of mistakes on a specific group of centers by unspecific ones takes place. Stereochemical enhancement of specificity requires the presence in the recognition protein molecule of a mechanism of switching on - off interaction on a group of centers. The most universal method of such switching on - off is a conformational transition in the protein molecule and (or) the "substrate".