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Helix bundles and coiled coils in α‐spectrin and tropomyosin: A theoretical CD study
Author(s) -
Bode Kimberly A.,
Applequist Jon
Publication year - 1997
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/(sici)1097-0282(199712)42:7<855::aid-bip10>3.0.co;2-8
Subject(s) - chemistry , helix (gastropod) , crystallography , helix bundle , tropomyosin , bundle , coiled coil , torsion (gastropod) , alpha helix , spectrin , spectral line , dihedral angle , protein structure , circular dichroism , physics , hydrogen bond , molecule , materials science , actin , anatomy , cytoskeleton , snail , cell , ecology , composite material , biochemistry , medicine , astronomy , organic chemistry , biology
The dipole interaction model is used to investigate the effects of interactions between helices and supertwisting of helices by determining whether the predicted UV absorption and CD spectra for the three‐helix bundle and coiled coil are significantly different from spectra for the single straight α‐helix. Crystallographic data by Yan et al. for α‐spectrin are used to construct a three‐helix bundle of poly( L ‐alanine) modeling the protein. Backbone torsion angles represented by Fourier series are used to generate supertwisted helices and coiled coil models of poly( L ‐alanine) that have pitch, radius, and residue repeat similar to experimental crystallographic data on tropomyosin. Calculated CD spectra are compared with available experimental data. Theoretical spectra for the three‐helix bundle and the supertwisted structures are quite similar to predictions for the straight α‐helix of the same length with similar torsion angles, suggesting that CD is primarily dependent on the average backbone conformation and would not be a sensitive tool for distinguishing between single straight helices and closely packed or twisted α‐helices. © 1997 John Wiley & Sons, Inc. Biopoly 42: 855–860, 1997