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Calculated compression, bending, shearing, torsion, and base‐tilting force constants of B‐ and A‐form poly(dG)·poly(dC)
Author(s) -
Putnam B. F.,
Prohofsky E. W.,
Zandt L. L. Van
Publication year - 1982
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360210503
Subject(s) - torsion constant , torsion (gastropod) , chemistry , coulomb , force field (fiction) , transverse plane , molecular physics , dna supercoil , deflection (physics) , shear force , force constant , classical mechanics , physics , torsion spring , dna , quantum mechanics , structural engineering , molecule , medicine , biochemistry , dna replication , surgery , organic chemistry , engineering , electron
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.