X-ray-diffraction analysis of oriented, partially crystalline fibres of polyinosinic acid has resulted in a new molecular model. This model consists of four identical polynucleotide chains related to one another by a fourfold rotation axis. The coaxial helices are righthanded (screw symmetry 232) and have an axial translation per residue h=0.341nm and a rotation per residue t=31.3°. Incorporated in the model are standard bond lengths, bond angles and C-2-endo furanose rings. The nucleotide conformation angles, determined by linked-atom least-squares methods, are orthodox and the fit with the X-ray intensities is good. Each hypoxanthine base is linked to two others by hydrogen bonds involving O-6 and N-1. Further stability may arise from intrachain hydrogen bonds between each ribose hydroxyl group and the phosphate oxygen O-3. If guanine were to be substituted for hypoxanthine in an isogeometrical molecular structure, additional hydrogen bonds could be made between every N-2 and N-7.
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Research Article| August 01 1974
Structures for polyinosinic acid and polyguanylic acid
Biochem J (1974) 141 (2): 537–543.
Struther Arnott, Rengaswami Chandrasekaran, Constance M. Marttila; Structures for polyinosinic acid and polyguanylic acid. Biochem J 1 August 1974; 141 (2): 537–543. doi: https://doi.org/10.1042/bj1410537
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