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A carbon‐13 magnetic resonance study of the helix–coil transition in polyuridylic acid
Author(s) -
Govil Girjesh,
Smith Ian C. P.
Publication year - 1973
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.1973.360121111
Subject(s) - chemistry , intramolecular force , random coil , randomness , spectral line , crystallography , dipole , electromagnetic coil , nuclear magnetic resonance , rotation (mathematics) , carbon 13 , chemical shift , flexibility (engineering) , resonance (particle physics) , chemical physics , stereochemistry , atomic physics , physics , circular dichroism , organic chemistry , statistics , mathematics , geometry , quantum mechanics , astronomy
The temperature‐dependent conformations of poly(U) in 0.5 M CsC1 have been studied by carbon‐13 nuclear magnetic resonance. The transition from random coil to an ordered structure results in broadening of lines in the 13 C spectra, due to intramolecular 1 H– 13 C dipolar interactions and restricted motions in the ordered state. Changes in the chemical shifts suggest that the bases are interacting below the transition temperature. The random coil form shows conformation preferences for internal rotation about C4′–C5′, C5′–O5′, and C3′–O 3′ bonds. The statistical randomness of the coil arises mainly because of flexibility about O–P bonds. The results are analyzed in conjunction with theoretical calculations and light‐scattering data.