title: Structural features and hydration of d(C-G-C-G-A-A-T-T-A-G-C-G); a double helix containing two G.A mispairs.
abstract: Single crystal X-ray diffraction techniques have been used to characterise the molecular structure of the title compound to 2.5A resolution. The structure consists of ten standard Watson-Crick base pairs and two G.A mismatched base pairs. The purine-purine mismatches have guanine in the usual anti orientation with respect to the sugar and adenine in syn orientation. There are two hydrogen bonds formed between the mismatch bases, N-1 and O-6 of guanine with N-7 and N-6 of adenine respectively. The bulky purine-purine mismatches are accommodated with minor perturbation of the sugar-phosphate backbone. There is a slight improvement in base pair overlap at the mismatch sites. Details of the backbone conformation, base stacking interactions and hydration are presented and compared with those of the parent compound d(C-G-C-G-A-A-T-T-C-G-C-G).
authors.affiliation: Chemical Laboratory, University of Cambridge, UK.
authors.forename: W N
authors.initials: WN
authors.lastname: Hunter
authors.forename: T
authors.initials: T
authors.lastname: Brown
authors.forename: O
authors.initials: O
authors.lastname: Kennard
mesh_terms: D001482:Base Composition; D003460:Crystallization; D004247:DNA; D014644:Genetic Variation; D006358:Hot Temperature; D006860:Hydrogen Bonding; D009690:Nucleic Acid Conformation; D014867:Water
chemical_list: D014867:Water; D004247:DNA