title: Analysis of conformational parameters in nucleic acid fragments. II. Co-crystal complexes of nucleic acid bases.
abstract: Studies have been made of conformational parameters in co-crystal complexes and compounds of nucleic acid bases in which there is the possibility of formation of hetero-base-pairs. Using published data extracted from the Cambridge structural database, a total of 37 base-pairs were found, of which 25 were hetero-pairs and 12 homo-pairs. These base-pairs were subject to analysis to reveal hydrogen bond parameters, propeller twist, buckle and C1'-C1' separation (or a similar parameter if C1' atoms were not present). Hetero-pairs were found to show larger twists than homo-pairs, the magnitude of twist being unrelated to hydrogen bond parameters or buckle value. The propeller twisting is less pronounced in these nucleic acid bases than in nucleosides, but still has a significant magnitude. Propeller twisting in hetero-pairs is found to be larger than in homo-pairs. Hetero-pairs appear to be formed preferentially in competitive situations.
authors.affiliation: Neutron Division, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK.
authors.forename: C C
authors.initials: CC
authors.lastname: Wilson
mesh_terms: D003460:Crystallization; D006860:Hydrogen Bonding; D009690:Nucleic Acid Conformation; D011687:Purines; D011743:Pyrimidines
chemical_list: D011687:Purines; D011743:Pyrimidines