CLEAVAGE OF SUBSTRATES CONTAINING MODIFIED AMINO GROUPS

IN HETEROCYCLIC BASES BY MvaI AND EcoRII RESTRICTION

ENDONUCLEASES

E. A. KUBAREVA, E. S. GROMOVA, E. A. ROMANOVA, T. S. ORETSKAYA, Z. A. SHABAROVA

Department of Chemistry, M. V. Lomonosov Moscow State University, Moscow

Abstract: 14-membcred DNA-duplexes containing modified nucleoside residues, viz 4-N-inethyldeoxycytidine (m⁴dC), 6-N-methyldeoxyadenosine (m⁶dA) or deoxyinosine (dI), in only one strand of the recognition site (CC^A/_TGG) of Mval and EcoRII endonucleases were synthesized. It was shown that Mval and EcoRII endonucleases interact with the cxocyclic amino groups of the external dC residues and of the central dA residue of the recognition site exposed into the DNA major groove. These endonucleases which are isochizomers were found to possess different mechanisms of substrate cleavage. The ability of Mva1 endonuclease to hydrolyze only unmodified strand of methylated duplexes allows one to make site-directed single-strand nicks in double-stranded DNA. Elimination of the 2-NH₂-group located in the minor groove of DNA by substituting dI for dG had little, if any, effect on the hydrolytic activity of EcoRII and Mva1 .endonucleases.

Russian Journal of Bioorganic Chemistry 1990, 16 (4):501-506

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