IDENTIFICATION OF SLOW MOTIONS IN THE REDUCED RECOMBINANT HIGH-POTENTIAL-IRON-SULFUR PROTEIN-I (HIPIP-I) FROM ECTOTHIORHODOSPIRA-HALOPHILA VIA N-15 ROTATING-FRAME NMR RELAXATION MEASUREMENTS
L. Banci et al., IDENTIFICATION OF SLOW MOTIONS IN THE REDUCED RECOMBINANT HIGH-POTENTIAL-IRON-SULFUR PROTEIN-I (HIPIP-I) FROM ECTOTHIORHODOSPIRA-HALOPHILA VIA N-15 ROTATING-FRAME NMR RELAXATION MEASUREMENTS, Journal of biomolecular NMR, 12(2), 1998, pp. 307-318
Rotating-frame N-15 relaxation rate (R-1 rho) NMR experiments have bee
n performed in order to study the dynamic behavior of the reduced reco
mbinant high-potential iron-sulfur protein iso I (HiPIP I) from Ectoth
iorhodospira halophila, in the mu s to ms time range. Measurements of
R-1 rho were perfomed as a function of the effective spin lock magneti
c field amplitude by using both on and off-resonance radio frequency i
rradiation. The two data sets provided consistent results and were fit
globally in order to identify possible exchange processes in an exter
nal loop of the reduced HiPIP I. The loop consists of residues 43-45 a
nd the correlation time of the exchange process was determined to be 5
0 +/- 8 mu s for the backbone nitrogen of Gln 44.