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Hydration effects on dynamics of polyglycine and sodium poly( L ‐glutamate)
Author(s) -
Kennedy Scott D.,
Bryant Robert G.
Publication year - 1990
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.360300705
Subject(s) - chemistry , molecular dynamics , proton , sodium , crystallography , magic angle spinning , nuclear magnetic resonance , computational chemistry , stereochemistry , nuclear magnetic resonance spectroscopy , organic chemistry , physics , quantum mechanics
Solid state nmr methods were applied to the study of the motions and structural heterogeneity in polyglycine, sodium poly (L‐glutamate), and poly(L‐alanine). The response of both the main‐chain and side‐chain resonances to the addition of water was studied using static and magic‐angle sample‐spinning line shapes as well as the carbon spin‐lattice relaxation times, the proton spin‐lattice relaxation time in the rotating frame, and the proton‐carbon cross‐polarization time. The polyglycine motions are not drastically affected by the addition of water when the polymer is in the 3 1 ‐helix or the β‐sheet structure. The sodium poly(L‐glutamate), however, responds to increased hydration with little motion in the main‐chain carbon atoms, but considerable flexibility of the side‐chain atoms. The greatest motions are reported for the C 5 carbon with rotational amplitudes about the C 47 ‐C 5 bond of about of 50°. In addition, motions somewhat less than half this size are required closer to the main chain.