Spatial configurations of polynucleotide chains. III. Polydeoxyribonucleotides

✍ Scribed by Wilma K. Olson; Paul J. Flory

• Publisher: Wiley (John Wiley & Sons)
• Year: 1972
• Tongue: English
• Weight: 566 KB
• Volume: 11
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1972.360110104

✦ Synopsis

The virtual bond scheme set forth in preceding papers for treating the average properties of polyriboadenylic acid (poly rA) is here applied to the calculation of the unperturbed mean-square end-to-end distance of polydeoxyriboadenylic acid (poly dA). The modifications in structure and in charge distribution resulting from the replacement of the hydroxyl group a t Cv in the ribose residue by hydrogen in deoxyribose produce only minor modifications in the conformational energies associated with the poly dA chain as compared to those found for poly rA. The main difference is manifested in the energy associated with rotations about the c 3 8 -0 3 ' bond of the deoxyribose residue in the Capendo conformation; accessible rotations are confined to the range between 0" and 30" relative to the trans conformation, whereas in the ribose unit the accessible regions comprise two ranges centered a t approximately 3.5' and 8.3". The characteristic ratio (rZ)o/nF calculated on the basis of the conformational energy estimates is =9 for the poly dA chain with all deoxyribose residues in the Cpendo conformation and =21 with all residues in the Czt-endo form. Satisfactory agreement is achieved between the theoretical values and experimental results on apurinic acid by treating the poly dA chain as a random copolymer of Cpendo and Cp-endo conformational isomers present in a ratio of -1 to 9.

* From the thesis submitted by Wilma K. Olson in fulfillment of the requirements for the degree of Doctor of