Calculated compression, bending, shearing, torsion, and base-tilting force constants of B- and A-form poly(dG)·poly(dC)
✍ Scribed by B. F. Putnam; E. W. Prohofsky; L. L. Van Zandt
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1982
- Tongue
- English
- Weight
- 615 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
Force constants associated with large‐scale motions of the DNA double‐helical homopolymer poly(dG)·poly(dC) are projected out of a long‐range atom–atom Coulomb force field. Force constants for both B‐ and A‐conformations have been calculated. Using the Coulomb interaction as previously incorporated into our DNA normal mode calculations, we obtain the forces determined by this long‐range interaction. These include compression, bending, shearing, torsion, and base tilting. We show, quantitatively, how the shearing and torsional transverse interactions fall off with intercell distance more rapidly than the compressional (longitudinal) interactions. Reasonable values for the elastic moduli of B‐ and A‐DNA are calculated. An important prediction of the present interaction theory is that although the single adjustable strength parameter in the Coulomb force field was chosen so as to reproduce an experimental value for the longitudinal sound velocity, the transverse torsional potential resulting from this fitted force field is in excellent agreement with results reported from supercoiling data and fluorescence measurements.