Internal motion time scales of a small, highly stable and disulfide-rich protein: a 15N, 13C NMR and molecular dynamics study.

摘要: Motions of the backbone CαHα and threonine CβHβ bonds toxin α were investigated using natural abundance 13C NMR molecular dynamics. Measurement longitudinal transverse relaxation rates employed ACCORDION techniques together with coherence selection by pulsed field gradients sensitivity enhancement through use preservation equivalent pathway, thus allowing a considerable reduction required spectrometer time. R1, R2, 1H→13C NOE obtained, as well variations R1ρ(90° ) function rf strength. These data compared to those recorded 1H 15N on labelled sample [Guenneugues et al. (1997) Biochemistry, 36, 16097–16108]. Both sets showed that picosecond nanosecond time scale motions are correlated secondary structure protein. This was further reinforced analysis 1 ns dynamics simulation in water. Several experimentally exhibit fast correlation longer than 500 ps, cannot be sampled along simulation. In addition, exhibits microsecond millisecond more half its length. Thus, α, highly stable protein (Tm=75 °C at acidic pH) containing 61 amino acids 4 disulfides, shows important internal scales ranging from 0.1–0.5 10–100 ns, about 30 μs 10 ms.