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Deuterium nuclear magnetic resonance of specifically labeled native collagen: investigation of protein molecular dynamics using quadrupolar echo technique

Journal Article · · Biophys. J.; (United States)
Collagen was labeled with )3,3,3-d/sub 3/) alanine and with (d/sub 10/) eucine via tissue culture. /sup 2/H nuclear magnetic resonance (NMR) spectra were obtained of collagen in solution and as fibrils using the quadrupolar echo techniqe. The /sup 2/H NMR data for (3,3,3-d/sub 3/)alanine-labeled collagen fibrils were analyzed in terms of a model for motion in which the molecule is considered to ump between two sites, separated azimuthally by an angle 2delta, in a time which is rapid compared with the residence time in both sites. The data suggest that the molecule undergoes reorientation over an angle, 2 delta, of approx. 30/sup 0/ in the fibrils, and that the average angle between the alanine C/sup ..cap alpha../-C/sup ..beta../ bond axis and the long axis of the helix is approx. 75/sup 0/. Reorientation is possibly segmental. The T/sub 2/ for (3,3,3-d/sub 3/)alanine-labeled collagen fibrils was estimated to be 105 ..mu..s. The /sup 2/H NMR data for the methyl groups of (d/sub 10/)leucine-labeled collagen were analyzed qualitatively. These data established that for collagen in solution and as fibrils, rotation occurs about the leucine side-chain bonds, in addition to threefold methyl rotation and reorientation of the peptide backbone. The T/sub 2/ for the methyl groups of leucine-labeled collagen is estimated to be approx. 130 ..mu..s. Taken together, these data provide strong evidence that both polypeptide backbone reorientation and amino acid side-chain motion occur in collagen molecules in the fibrils. Stabilizing interactions that determine fibril structure must therefore depend upon at least two sets of contacts in any given local region.
Research Organization:
National Institutes of Health, Bethesda, MD
OSTI ID:
7032448
Journal Information:
Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 32:1; ISSN BIOJA
Country of Publication:
United States
Language:
English