ABSTRACT
Photoaffinity modification experiments are characterized by specific features since the reactions are carried out in the transparent media only and UV-excited groups of reagents and biopolymers can be involved in many specific and nonspecific reactions. Affinity modification with photoactivatable reagents usually yields a low extent of biopolymer modification. To study the physical chemistry of a process of biopolymer modification, it is necessary to obtain quantitative characteristics of the process. The performance of photoaffinity modification at very low temperatures was proposed to suppress the dissociation of a reagent from the complex with biopolymer molecules and to prevent the thermoinactivation of a biopolymer in the course of irradiation. Indeed, investigation of stability of the biopolymer under irradiation conditions in the absence of an affinity reagent is the standard control of the affinity modification experiments. A simplified experimental version of such analysis which allows easy identification of spots containing modified biopolymer molecules is the diagonal electrophoresis method.
