13CHD2 methyl group probes of millisecond time scale exchange in proteins by 1H relaxation dispersion: an application to proteasome gating residue dynamics.
A pulse scheme is presented for quantifying millisecond time scale chemical exchange processes in proteins by measuring (1)H CPMG relaxation dispersion profiles of (13)CHD(2) methyl groups. The use of (13)CHD(2) isotopomers for (1)H methyl dispersion experiments eliminates problems with interconversion between differentially relaxing proton transitions that complicate the extraction of accurate exchange parameters when (13)CH(3) probes are used. Good agreement is demonstrated between extracted chemical shift differences from fits of dispersion profiles and the corresponding differences measured independently on a model exchanging system, validating the experiment. The methodology is applied to the gating residues of the T. acidiphilium proteasome that are shown to undergo extensive motion on the millisecond time scale.
Baldwin
Andrew J
AJ
Department of Molecular Genetics, The University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
Religa
Tomasz L
TL
Hansen
D Flemming
DF
Bouvignies
Guillaume
G
Kay
Lewis E
LE
D003903:Deuterium / Q000737:chemistry*; D007700:Kinetics; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry*; D011487:Protein Conformation; D013822:Thermoplasma / Q000201:enzymology
D003903:Deuterium; D046988:Proteasome Endopeptidase Complex; D008697:Methane