This image illustrates the chemical structure of a purine molecule, highlighting the numbering of the carbon and nitrogen atoms. The purine structure consists of a pyrimidine ring (positions 1 to 6) ...

One of the pair must be a purine and the other a pyrimidine ... we devised our structure, which rests mainly though not entirely on published experimental data and stereo-chemical arguments.

This diagram depicts the chemical structure of pyrimidine, a six-membered aromatic ring with two nitrogen atoms at positions 1 and 3 (highlighted in blue). The remaining positions are occupied by ...

Laying the Groundwork: Levene Investigates the Structure of DNA Meanwhile ... In other words, the total amount of purines (A + G) and the total amount of pyrimidines (C + T) are usually nearly ...