Open AccessAnalysis of Backbone Dynamics in Cytochrome b 5 using 15 N‐NMR Relaxation Measurements
Author(s) -
Kelly Geoffrey P.,
Muskett Frederick W.,
Whitford David
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00349.x
Subject(s) - heteronuclear molecule , microsecond , relaxation (psychology) , chemistry , nanosecond , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , crystallography , nuclear overhauser effect , stereochemistry , physics , psychology , social psychology , laser , astronomy , optics
Determination of 15 N‐NMR relaxation rates has allowed the characterisation of the dynamic properties of 55 1 H‐ 15 N bond vectors in a soluble haem‐binding domain of bovine microsomal ferricytochrome b 5 consisting of the first 104 amino acid residues. Measurements of heteronuclear { 1 H}‐ 15 N‐NMR nuclear Overhauser effects, and 15 N‐NMR longitudinal and transverse relaxation rates have been analysed using both model‐free and reduced spectral density mapping approaches, demonstrating the application of these methods to a paramagnetic system. Analysis reveals that, for those regions which have been assessed, the polypeptide backbone of ferricytochrome b 5 is largely rigid (average S 2 = 0.80), and that minimal internal backbone motion occurs on the sub‐nanosecond timescale. In contrast, motions on the microsecond to millisecond timescale, especially pronounced for the loop region extending from residues 28 to 31, and which may be of biological relevance, are indicated.