Interbase dihedral angle

Very few structural studies have been concentrated on models of ApG adducts of cisplatin. Conformational analysis of two rotameric forms of the complex m-[Pt(NH3)2(9-MeA-A(7))(9-EtGH-A(7))]2+ has recently been described [40], One of the forms, crystallized as a PI 6 salt, can be characterized as a right-handed helicoidal model for the intrastrand ApG crosslink in double-stranded DNA. The bases in this compound assume a head-to-head orientation (Fig. 6) with the interbase dihedral angles of 81.8° and 87.5°. There are two independent complex cations in the unit cell. The left-... 

From Figure 3, it is clear that the B/B interbase conformational angle (as well as the B/PtN dihedral angle) decreases significantly on going from the bis(nucleobase) complex, through the bis(nucleoside) complex, to the bis(nucleotide) complex. 

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