A highly propeller-twisted adenine-adenine base pair in 8-tert-butyladenine.
C9H13N5, Mr = 191.24, monoclinic, P2(1)/c, a = 7.562 (1), b = 6.825 (1), c = 20.905 (1) A, beta = 104.84 (1) degree, V = 1042.9 A3, Z = 4, room temperature, Dx = 1.218 g cm-3, lambda (Cu K alpha) = 1.5418 A, mu = 6.6 cm-1, F(000) = 408. The structure was solved by the multisolution technique and refined by the block-diagonal least-squares method to a final R index of 0.045 using 1970 intensities. The adenine bases form three pairs of hydrogen bonds to symmetry-related molecules in the crystal lattice. Two distinct modes of hydrogen bonding are observed. One mode involves a planar interaction between adjacent adenine bases while the second mode is characterized by an unusually high propeller twist angle of 79.3 degrees between the planes through the two participating adenine bases.
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706.
A
A
Alexandrescu
W B
WB
Drendel
M
M
Sundaralingam
D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry*; D001482:Base Composition; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D014961:X-Ray Diffraction
C071611:8-tert-butyladenine; D000225:Adenine