Premium
15 N T 2 ′ relaxation times of bacteriorhodopsin transmembrane amide nitrogens
Author(s) -
Soubias Olivier,
Réat Valérie,
Saurel Olivier,
Milon Alain
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.1332
Subject(s) - bacteriorhodopsin , chemistry , crystallography , amide , bilayer , lipid bilayer , relaxation (psychology) , pulse sequence , transmembrane protein , dimer , monomer , membrane , helix (gastropod) , analytical chemistry (journal) , nuclear magnetic resonance , stereochemistry , organic chemistry , psychology , social psychology , ecology , biochemistry , physics , receptor , snail , biology , polymer
15 N T 2 ′ relaxation times of bacteriorhodopsin (BR) amide nitrogens were determined in the temperature range from 40 to −60°C using a Hahn echo pulse sequence and proton decoupling during the echo and detection times. Using oriented membrane samples, with their bilayer normal parallel to the external magnetic field, the 15 N amide nitrogens belonging to the transmembrane helices could be selected for the analysis. The experiments were performed on purple membrane fragments (in which BR is organized in a 2D crystalline network) and on BR reconstituted into dimyristoylphosphatidylcholine at a 1:150 molar ratio (in which BR is in a freely diffusing monomeric state at 40°C and in an aggregated state at 4°C and below). The results are discussed in terms of helix dynamics, mosaic spread and resolution of the 15 N spectra for the various samples and experimental conditions. Copyright © 2004 John Wiley & Sons, Ltd.