Crystal structure of an intermolecular 2:1 complex between adenine and thymine. Evidence for both Hoogsteen and 'quasi-Watson-Crick' interactions.
The titled complex, obtained by co-crystallization (EtOH/25 degrees C), is apparently the only known complex of the free bases. Its crystal structure, as determined by X-ray diffraction at both 90 K and 313 K, showed that one A-T pair involves a Hoogsteen interaction, and the other a Watson-Crick interaction but only with respect to the adenine unit. The absence of a clear-cut Watson-Crick base pair raises intriguing questions about the basis of the DNA double helix.
Chandrasekhar
Sosale
S
Department of Organic Chemistry, Indian Institute of Science, Bangalore, India. sosale@orgchem.iisc.ernet.in
Naik
Tangali R Ravikumar
TR
Nayak
Susanta K
SK
Row
Tayur N Guru
TN
D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D013696:Temperature; D013941:Thymine / Q000737:chemistry*
D004247:DNA; D000225:Adenine; D013941:Thymine