Effect of BII phosphate groups on DNA groove dimensions.

The groove dimensions (in Å, standard deviations in parentheses) were measured on 139 complementary dinucleotides NpN•NpN (N: any nucleotide) in 28 high resolution X-ray structures of free decamers (list provided in Supporting Information S1). The dinucleotides are categorized according to the conformational states of their central and 3′/5′-phosphate linkages. BII phosphates are boxed. The number of occurrences in each category is given by n. The standard deviation for n = 2 is still reported, since the groove dimensions are measured at four points along one dinucleotide step [46].