I first came to know about the Hoogsteen bp from Saenger's book ("Principles of Nucleic Acid Structure"). Over the years, I have read many articles mentioning the Hoogsteen bp and touched this topic myself in the 2003 3DNA NAR publication. However, I have never read Hoogsteen's two original publications on this topic until recently:
- The two-page long preliminary report, titled "The structure of crystals containing a hydrogen-bonded complex of 1-methylthymine and 9-methyladenine", was published in Acta Cryst. (1959). 12, 822-3. The paper contained only a single reference to the Watson-Crick DNA structure paper, published in Nature in 1953. I found it very revealing to understand why Hoogsteen used the methyl-ed derivatives of thymine and adenine, and how the failed initial interpretation of the experimental "vector-density map" using the Watson-Crick A-T bp led to the discovery of the new base-pairing scheme:
The fact that the first trial structure could not be refined led to a more critical scrutiny of the generalized projection and a greater emphasis on the significance of certain spurious peaks and on relatively large variations in the heights of peaks that were assumed to represent atoms. The correct structure was finally discovered by changing the positions of a few atoms in the 9-methyladenine portion of the asymmetric unit.
- The more extensive account of the Hoogsteen bp story, titled "The Crystal and Molecular Structure of a Hydrogen-Bonded Complex Between 1-Methylthymine and 9-Methyladenine", published in Acta Cryst. (1963) 16, 907-16.
As a side note, the term Hoogsteen "edge" appears quite frequently in today's publications of RNA structures: in the Leontis-Westhof bp classification scheme, the term simply means the major groove edge in what would be a Watson-Crick bp geometry.