Demethylamination of N6-methyldeoxyadenosine by commercial spleen phosphodiesterase preparations

Commercial spleen phosphodiesterase preparations contain an activity (presumably enzymatic) that will deaminate adenosine, deoxyadenosine and demethylaminate N⁶-methyldeoxyadenosine but not their 3′ -or 5′-phosphates. The product obtained by the enzymic demethylamination of N⁶-methyldeoxyadenosine was identified as deoxyinosine on the basis of its electrophoretic mobility and its ultraviolet spectrum. The presence of a deaminase activity in spleen phosphodiesterase preparations must be considered when using the enzyme in nucleotide sequence studies.