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Macromolecule Structure Refinement by Relaxation Matrix Analysis of 2D NOE Spectra: Effect of Differential Internal Motion on Internuclear Distance Determination in Proteins
Author(s) -
Kumar Anil,
James Thomas L.,
Levy George C.
Publication year - 1992
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199200032
Subject(s) - chemistry , homonuclear molecule , relaxation (psychology) , spectral line , molecular physics , dipole , proton , nuclear magnetic resonance , two dimensional nuclear magnetic resonance spectroscopy , nuclear overhauser effect , analytical chemistry (journal) , nuclear magnetic resonance spectroscopy , molecule , stereochemistry , physics , psychology , social psychology , organic chemistry , chromatography , quantum mechanics , astronomy
Interproton distances obtained from NMR experiments are used to determine the high‐resolution structure of biopolymers. The accuracy of internuclear distances extracted from proton homonuclear 2D NOE spectra can be improved by using a complete relaxation matrix analysis, taking into account all proton dipole‐dipole interactions as well as internal motions. The effect of internal motion on interproton distances, determined from the 2D NOE cross‐peak intensities, has been examined using a new version of the mardigras program, which iteratively determines interproton distances from experimental 2D NOE peak intensities using the complete relaxation matrix. The internal motion has been specified by the ‘model‐free’ approach in terms of an overall correlation time, local correlation times, and order parameters. Using a simulation for the 58‐residue protein bovine pancreatic trypsin inhibitor (BPTI), it is shown that if the local order parameter and correlation time for a given residue differ substantially (but within the experimentally determined range of values) from the average order parameter and correlation time, the error in the interproton distance may be as large as 0.6 Å.