LARMOR FREQUENCY-SELECTIVE MODEL-FREE ANALYSIS OF PROTEIN NMR RELAXATION

The Lipari-Szabo dynamical formalism is extended by setting the time c onstants of the Lorentzian terms to -1/omega(N) and 1/(omega(H) + omeg a(N)). This analysis is compared to the earlier proposed three-paramet er (S-f(2),S-s(2),tau(s)) extended model free formalism with regard to the range of equivalence and the advantages of the simplified two-par ameter (S-f(2),S-H(2)) and (S-f(2),S-N(2)) representations. Spectral d ensity components are calculated and compared to those obtained from t he spectral density analysis formalism. Protein relaxation data, commo nly analyzed in terms of the two-parameter (S-2,tau(e)) representation , may correspond to a dynamically heterogeneous behaviour that is more appropriately represented in terms of a fast limit order parameter an d a second, lower frequency order parameter.