Conformation of N6-Methyladenine, a Base Involved in DNA Modification: Restriction Processes

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Science  23 Nov 1973:
Vol. 182, Issue 4114, pp. 833-834
DOI: 10.1126/science.182.4114.833


Crystal structures of N6,N9-dimethyladenine and N6-methyladenine hydrochloride were determined from three-dimensional x-ray diffraction data. The bases assume a conformation in which the N(6)-methyl group blocks one of the hydrogen-bonding sites normally used by adenine to form Watson-Crick pairs with thymine in double-helical DNA. When in this conformation, N6-methyladenine residues might alter the secondary structure of DNA. thereby preventing the scission of modified DNA's by restriction enzymes.