ChemInform Abstract: Inhibitors of Bacillus subtilis DNA Polymerase III. Influence of Modifications in the Pyrimidine Ring of Anilino‐ and (Benzylamino)pyrimidines.

Abstract

Substituent effects governing inhibition of DNA polymerase III from Bacillus subtilis were examined in several series of N6-substituted 6-aminopyrimidines. The presence of alkyl groups as large as n-butyl in the 3-position of 6-(5-indanylamino)uracil had no effect on inhibitor-enzyme binding. Substituents in the 4-position of a series of 2-amino-6-(benzylamino)pyrimidines had complex effects: alkoxy and phenoxy derivatives were less than the parent 4-oxo (isocytosine) compound, but alkylphenoxy and halophenoxy derivatives were more than the 4-phenoxy compound itself, suggesting that hydrophobic binding can occur between 4-substitutents and the enzyme surface and that space between the pyrimidine ring and pol III may represent the site of the enzyme. Replacement of 5-H by methyl and ethyl groups drastically decreased inhibitory activity of 6-(benzylamino)- and 6-p-toluidinouracils, but 5-bromo and 5-iodo analogues were equipotent with the parent compounds. These results indicate that the phenyl rings of these compounds must exist in in which they are perpendicular to the pyrimidine ring plane and that charge-transfer stabilization of such active conformations may compensate for steric barriers from 5-halo groups in the inhibitor-enzyme complex.