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Investigation of the dynamics of an elastin‐mimetic polypeptide using solid‐state NMR
Author(s) -
Yao Xiao L.,
Conticello Vincent P.,
Hong Mei
Publication year - 2004
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1330
Subject(s) - chemistry , elastin , elasticity (physics) , isotropy , microsecond , molecular dynamics , amplitude , solid state nuclear magnetic resonance , anisotropy , crystallography , conformational entropy , nuclear magnetic resonance , chemical physics , thermodynamics , computational chemistry , molecule , organic chemistry , physics , medicine , pathology , quantum mechanics , astronomy
Elastin is the main structural protein that provides elasticity to various tissues and organs in vertebrates. Molecular motions are believed to play a significant role in its elasticity. We have used solid‐state NMR spectroscopy to characterize the dynamics of an elastin‐mimetic protein as a function of hydration to better understand the origin of elastin elasticity. Poly(Lys‐25), [(VPGVG) 4 (VPGKG)] 39 , has a repeat sequence common to natural elastin. 13 C cross‐polarization and direct polarization spectra at various hydration levels indicate that water enhances the protein motion in a non‐uniform manner. Below 20% hydration, the backbone motion increases only slightly whereas above 30% hydration, both the backbone and the side‐chains undergo large‐amplitude motions. The motional amplitudes are extracted from 13 C– 1 H and 1 H– 1 H dipolar couplings using 2D isotropic–anisotropic correlation experiments. The root mean square fluctuation angles are found to be 11–18° in the dry protein and 16–21° in the 20% hydrated protein. Dramatically, the amplitudes increase to near isotropic at 30% hydration. Field‐dependent 1 H rotating‐frame spin–lattice relaxation times ( T 1ρ ) indicate that significant motions occur on the microsecond time‐scale (1.2–2.3 µs). The large‐amplitude and low‐frequency motion of poly(Lys‐25) at relatively mild hydration indicates that the conformational entropy of the protein in the relaxed state contributes significantly to the elasticity. Copyright © 2004 John Wiley & Sons, Ltd.