The incoherent quasi-elastic neutron scattering (IQNS) method is a useful technique to study biomolecular dynamics. The versatility of the method makes possible motional studies of biomolecules in different forms: powder, crystal, and solution; and at different temperatures. Thus, it allows for the investigation of biomolecular dynamics over a wide-range of physical conditions. We have used the IQNS method to study the motions of side chains in trypsin and myoglobin at various D$\sb2$O hydration levels. The scattering spectra S(Q,$\omega$) were measured in constant-Q mode. The protein in powder form exhibits vibrational high-frequency motions, while the protein in solution and in crystals are characterized by diffusive jumps, and high-frequency vibrations. At temperatures below 200K, the S(Q,$\omega$) for these proteins in solution is similar to an harmonic solid. As temperature increases, a transition is seen at 200K, above which the protein becomes more liquid-like with rapid transitions between conformational substates. The diffusion constant D for the side chains is on the order of 10$\sp{-6}$ cm$\sp2$/sec.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/16803 |
| Date | January 1995 |
| Creators | Cao, Hung Duc |
| Contributors | Huang, Huey W. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 88 p., application/pdf |
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