Larmor frequency selective model free analysis of protein NMR relaxation.
The Lipari-Szabo dynamical formalism is extended by setting the time constants of the Lorentzian terms to [Formula: see text] and [Formula: see text]. This analysis is compared to the earlier proposed three-parameter [Formula: see text] extended model free formalism with regard to the range of equivalence and the advantages of the simplified two-parameter (S (inff)           (sup2) ,S (infH)           (sup2) ) and (S (inff)           (sup2) ,S (infN)           (sup2) ) representations. Spectral density components are calculated and compared to those obtained from the spectral density analysis formalism. Protein relaxation data, commonly analyzed in terms of the two-parameter [Formula: see text] representation, may correspond to a dynamically heterogeneous behaviour that is more appropriately represented in terms of a fast limit order parameter and a second, lower frequency order parameter.
Department of Biochemistry, University of Wisconsin-Madison, 420 Henry Mall, 53706-1569, Madison, WI, U.S.A..
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Lemaster