Abstract:
:A pulsed source neutron spectrometer has been used to measure vibrational spectra (20-4000 cm-1) of dry and hydrated type I collagen fibers, and of two model polypeptides, polyproline II and (prolyl-prolyl-glycine)10, at temperatures of 30 and 120 K. the collagen spectra provide the first high resolution neutron views of the proton-dominated modes of a protein over a wide energy range from the low frequency phonon region to the rich spectrum of localized high frequency modes. Several bands show a level of fine structure approaching that of optical data. The principal features of the spectra are assigned. A difference spectrum is obtained for protein associated water, which displays an acoustic peak similar to pure ice and a librational band shifted to lower frequency by the influence of the protein. Hydrogen-weighted densities of states are extracted for collagen and the model polypeptides, and compared with published calculations. Proton mean-square displacements are calculated from Debye-Waller factors measured in parallel quasi-elastic neutron-scattering experiments. Combined with the collagen density of states function, these yield an effective mass of 14.5 a.m.u. for the low frequency harmonic oscillators, indicating that the extended atom approximation, which simplifies analyses of low frequency protein dynamics, is appropriate.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Middendorf HD,Hayward RL,Parker SF,Bradshaw J,Miller Adoi
10.1016/S0006-3495(95)79942-8subject
Has Abstractpub_date
1995-08-01 00:00:00pages
660-73issue
2eissn
0006-3495issn
1542-0086pii
S0006-3495(95)79942-8journal_volume
69pub_type
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