[Conformational heterogeneity of tRNA, detected in the reaction of guanine bases with ketoxal].

The study of kinetic characteristics of the reaction of tRNA guanine bases with kethoxal has shown that temperature, ionic strength and Mg2+ ions, i.e. factors directly affecting the spatial structure of tRNA, influence also on its internal modification. The modification degree under stabilized spatial tRNA structure depends also on the concentration of kethoxal and is expressed in fractional values of the number of modified guanosine residues per tRNA molecule, which indicates the heterogeneity of tRNA for the modification degree. Chromatography of tRNA1 Val preparation on BD cellulose after the exhaustive modification with kethoxal under conditions of stabilized spatial structure has revealed a fraction of molecules completely resistant to the modificator, and a fraction containing differently modified tRNA molecules. tRNA heterogeneity after the reaction with kethoxal (the presence of resistant and reactive forms) indicates conformational heterogeneity of tRNA, expressed in the simultaneous presence of at least two conformer families.