Conformations of complexes between mitomycins and decanucleotides. 3. Sequence specificity, binding at C-10, and mitomycin analogues.

Molecular mechanics simulation of the interactions of mitomycin C and certain analogues with DNA models are presented. The sequence specificity of mitomycin C binding was investigated by using a d(GCGCGCGCGC)2 decanucleotide duplex, abbreviated herein as GC10, in which the base pair was varied on either side of the covalent binding site. A CGT fragment was favored, although its correlation with the diverse findings in the literature is questionable. A model was derived for the monocovalent binding at C10 of 2,7-diaminomitosene with GC10 and for the noncovalently bound hydroquinone intermediate. Revised models were established for three highly active mitomycin C analogues: M-83, BMY-25282, and RR-150. They involved covalent binding at the 2-amino group of a guanine residue, and they accounted for enhanced noncovalent binding afforded by specific interactions of the C7 substituents with residues in GC10.