TY - JOUR

T1 - A new spin probe of protein dynamics

T2 - Nitrogen relaxation in 15N-2H amide groups

AU - Xu, Jun

AU - Millet, Oscar

AU - Kay, Lewis E.

AU - Skrynnikov, Nikolai R.

PY - 2005/3/9

Y1 - 2005/3/9

N2 - 15N spin relaxation data have provided a wealth of information on protein dynamics in solution. Standard R1, R1ρ, and NOE experiments aimed at 15N[1H] amide moieties are complemented in this work by HA(CACO)N-type experiments allowing the measurement of nitrogen R1 and R1ρ rates at deuterated 15N[2D] sites. Difference rates obtained using this approach, R1(15N[1H]) - R1( 15N[2D]) and R2(15N[1H]) - R2(15N[2D]), depend exclusively on dipolar interactions and are insensitive to 15N CSA and Rex relaxation mechanisms. The methodology has been tested on a sample of peptostreptococcal protein L (63 residues) prepared in 50% H2O-50% D2O solvent. The results from the new and conventional experiments are found to be consistent, with respect to both local backbone dynamics and overall protein tumbling. Combining several data sets permits evaluation of the spectral density J(ωD + ωN) for each amide site. This spectral density samples a uniquely low frequency (26 MHz at a 500 MHz field) and, therefore, is expected to be highly useful for characterizing nanosecond time scale local motions. The spectral density mapping demonstrates that, in the case of protein L, J(ωD + ωN) values are compatible with the Lipari-Szabo interpretation of backbone dynamics based on the conventional 15N relaxation data.

AB - 15N spin relaxation data have provided a wealth of information on protein dynamics in solution. Standard R1, R1ρ, and NOE experiments aimed at 15N[1H] amide moieties are complemented in this work by HA(CACO)N-type experiments allowing the measurement of nitrogen R1 and R1ρ rates at deuterated 15N[2D] sites. Difference rates obtained using this approach, R1(15N[1H]) - R1( 15N[2D]) and R2(15N[1H]) - R2(15N[2D]), depend exclusively on dipolar interactions and are insensitive to 15N CSA and Rex relaxation mechanisms. The methodology has been tested on a sample of peptostreptococcal protein L (63 residues) prepared in 50% H2O-50% D2O solvent. The results from the new and conventional experiments are found to be consistent, with respect to both local backbone dynamics and overall protein tumbling. Combining several data sets permits evaluation of the spectral density J(ωD + ωN) for each amide site. This spectral density samples a uniquely low frequency (26 MHz at a 500 MHz field) and, therefore, is expected to be highly useful for characterizing nanosecond time scale local motions. The spectral density mapping demonstrates that, in the case of protein L, J(ωD + ωN) values are compatible with the Lipari-Szabo interpretation of backbone dynamics based on the conventional 15N relaxation data.

UR - http://www.scopus.com/inward/record.url?scp=14844333088&partnerID=8YFLogxK

U2 - 10.1021/ja040215z

DO - 10.1021/ja040215z

M3 - Article

C2 - 15740163

AN - SCOPUS:14844333088

VL - 127

SP - 3220

EP - 3229

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 9

ER -