title: On the use of the phase memory time T2 for the quantitative characterization of the rotational motions of proteins in lipid bilayer systems.
abstract: Numerical simulations of the echo responses from a nitroxide label rigidly attached to a large protein undergoing ultraslow rotational motions in a lipid bilayer are presented. The echoes are formed by the application of Hahn, COSY, and 2D-ELDOR sequences utilizing both soft and hard microwave pulses. The simulations address the question of whether the echo responses elicited by these sequences are affected by restricted angular excursions of the long axis of the protein relative to the normal to the bilayer plane. The results indicate that all three pulse sequences yield the same quantitative motional information regardless of the nature of the microwave pulses and there is no theoretical reason for preferring one sequence above the others.
authors.affiliation: Buys Ballot Laboratory, Debye Institute, Utrecht, 3508 TA, The Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: van der Struijf
authors.forename: Y K
authors.initials: YK
authors.lastname: Levine
mesh_terms: D000465:Algorithms; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy; D005583:Fourier Analysis; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects; D008280:Magnetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000528:radiation effects; D008872:Microwaves; D008958:Models, Molecular; D015203:Reproducibility of Results; D013113:Spin Labels
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins; D013113:Spin Labels; D000252:Calcium-Transporting ATPases