DSSR-derived G-quadruplex features in PDB entry 4r47
- X-ray (1.85 Å)
- Racemic crystal structure of a bimolecular DNA G-quadruplex (p21-n)
- Mandal, P.K., Collie, G.W., Kauffmann, B., Huc, I.: (2014) "Racemic DNA crystallography." Angew.Chem.Int.Ed.Engl., 53, 14424-14427.
- Racemates increase the chances of crystallization by allowing molecular contacts to be formed in a greater number of ways. With the advent of protein synthesis, the production of protein racemates and racemic-protein crystallography are now possible. Curiously, racemic DNA crystallography had not been investigated despite the commercial availability of L- and D-deoxyribo-oligonucleotides. Here, we report a study into racemic DNA crystallography showing the strong propensity of racemic DNA mixtures to form racemic crystals. We describe racemic crystal structures of various DNA sequences and folded conformations, including duplexes, quadruplexes, and a four-way junction, showing that the advantages of racemic crystallography should extend to DNA.
- G4 notes
- 4 G-tetrads, 1 G4 helix, 1 G4 stem · (2+2), UDDU
1 glyco-bond=s--s groove=w-n- planarity=0.258 type=other nts=4 GGGG A.DG1001,B.DG2004,A.DG1012,B.DG2009 2 glyco-bond=-ss- groove=w-n- planarity=0.159 type=planar nts=4 GGGG A.DG1002,B.DG2003,A.DG1011,B.DG2010 3 glyco-bond=s--s groove=w-n- planarity=0.130 type=planar nts=4 GGGG A.DG1003,B.DG2002,A.DG1010,B.DG2011 4 glyco-bond=-ss- groove=w-n- planarity=0.267 type=bowl nts=4 GGGG A.DG1004,B.DG2001,A.DG1009,B.DG2012
In DSSR, a G4-helix is defined by stacking interactions of G-tetrads, regardless of backbone connectivity, and may contain more than one G4-stem.
Helix#1, 4 G-tetrad layers, inter-molecular, with 1 stem
In DSSR, a G4-stem is defined as a G4-helix with backbone connectivity. Bulges are also allowed along each of the four strands.