Microsecond Time Scale Mobility in a Solid Protein As Studied by the 15N R1ρ Site-Specific NMR Relaxation Rates
journal contributionposted on 01.09.2010, 00:00 by Alexey Krushelnitsky, Tatiana Zinkevich, Detlef Reichert, Veniamin Chevelkov, Bernd Reif
For the first time, we have demonstrated the site-resolved measurement of reliable (i.e., free of interfering effects) 15N R1ρ relaxation rates from a solid protein to extract dynamic information on the microsecond time scale. 15N R1ρ NMR relaxation rates were measured as a function of the residue number in a 15N,2H-enriched (with 10−20% back-exchanged protons at labile sites) microcrystalline SH3 domain of chicken α-spectrin. The experiments were performed at different temperatures and at different spin-lock frequencies, which were realized by on- and off-resonance spin-lock irradiation. The results obtained indicate that the interfering spin−spin contribution to the R1ρ rate in a perdeuterated protein is negligible even at low spin-lock fields, in contrast to the case for normal protonated samples. Through correlation plots, the R1ρ rates were compared with previous data for the same protein characterizing different kinds of internal mobility.