Dm. Lemaster et Dm. Kushlan, DYNAMICAL MAPPING OF ESCHERICHIA-COLI THIOREDOXIN VIA C-13 NMR RELAXATION ANALYSIS, Journal of the American Chemical Society, 118(39), 1996, pp. 9255-9264
NMR relaxation analysis was used to characterize the internal dynamics
of oxidized E. coli thioredoxin in both the picosecond-nanosecond and
microsecond-millisecond frequency ranges for 413 H-C and H-N bond vec
tors. The C-13 relaxation data was obtained utilizing protein samples
possessing an alternating C-13-C-12-C-13... labeling pattern for most
enriched sites. When combined with partial deuteration, this labeling
pattern provides for isolated H-1-C-13 IS spin pairs exhibiting dynami
cally interpretable relaxation behavior. Side chains were found to exh
ibit a far broader range of dynamics than have been previously charact
erized for main chain resonances. The dynamics of structurally buried
aromatic and leucine side chains are interpreted in terms of correlate
d main chain-side chain torsional oscillations. Structural regions exh
ibiting millisecond dynamics were found to correlate strongly with the
presence of side chain-main chain or bifurcated main chain hydrogen b
onds. Nuclei around the active site disulfide that exhibit mobility in
the millisecond range correspond closely to the set of nuclei whose c
hemical shifts are altered upon reduction. The transient conformation
is interpreted in terms of enhanced reactivity due to strain at the di
sulfide linkage.