Related Experiment Video
Updated: Jun 12, 2026

Iterative Optimization of DNA Duplexes for Crystallization of SeqA-DNA Complexes
Published on: November 1, 2012
Crystal structure of an intermolecular 2:1 complex between adenine and thymine. Evidence for both Hoogsteen and
Sosale Chandrasekhar1, Tangali R Ravikumar Naik, Susanta K Nayak
1Department of Organic Chemistry, Indian Institute of Science, Bangalore, India. sosale@orgchem.iisc.ernet.in
Abstract:
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.
Related Concept Videos
DNA Base Pairing
DNA Base Pairing
The DNA Helix
The DNA Helix
Nucleic Acid Structure
DNA Structure
DNA has a double-helix structure. The...
DNA as a Genetic Template

