[Determination of the adenine-specific methylase recognition site of Shigella sonnei 47, using hydrazinolysis with subsequent separation of purine oligonucleotides by thin layer chromatography on DEAE- cellulose]. / Opredelenie saita uznavaniia adeninspetsificheskoi metilazy Shigellasonnei 47 s pomoshch'iu gidrazinolizadnk i posleduiushchego pazdeleniia purinovykh oligonukleotidov tonkosloinoi khromatografiei na déaé-tselliuloze.

A procedure for separation of oligopurine blocks of different length and composition by two-dimensional thin layer chromatography on DEAE-cellulose plates has been developed. This method allows a comparative analysis of the purine isostich content in the DNAs of various origin. In case of methylated DNA, the method permits to compare the substrate specificity of different enzymes responsible for the adenine residue methylation in the DNA. In combination with enzymatic treatment of labeled methylated isostichs, the method described can be used for the deciphering of the methylated sequences as well as for constructing, in a number of cases, the recognition site of adenine-specific methylases. Thus, it was demonstrated that methylase SsoI recognizes the 5...G-A-A-T-T-C ... 3' sequence and methylates its adenine residue nearest to the 5'-end.