Sound Velocity and Elasticity of Tetragonal Lysozyme Crystals by Brillouin Spectroscopy

S. Speziale, F. Jiang, C. L. Caylor, S. Kriminski, C. S. Zha, R. E. Thorne, T. S. Duffy

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

Quasilongitudinal sound velocities and the second-order elastic moduli of tetragonal hen egg-white lysozyme crystals were determined as a function of relative humidity (RH) by Brillouin scattering. In hydrated crystals the measured sound velocities in the [110] plane vary between 2.12 ± 0.03 km/s along the [001] direction and 2.31 ± 0.08 km/s along the [110] direction. Dehydration from 98% to 67% RH increases the sound velocities and decreases the velocity anisotropy in (110) from 8.2% to 2.0%. A discontinuity in velocity and an inversion of the anisotropy is observed with increasing dehydration providing support for the existence of a structural transition below 88% RH. Brillouin linewidths can be described by a mechanical model in which the phonon is coupled to a relaxation mode of hydration water with a single relaxation time of 55 ± 5 ps. At equilibrium hydration (98% RH) the longitudinal moduli C11 + C12 + 2C66 = 12.81 ± 0.08 GPa, C11 = 5.49 ± 0.03 GPa, and C 33 = 5.48 ± 0.05 GPa were directly determined. Inversion of the measured sound velocities in the [110] plane constrains the combination C44 + 1/2C13 to 2.99 ± 0.05 GPa. Further constraints on the elastic tensor are obtained by combining the Brillouin quasilongitudinal results with axial compressibilities determined from high-pressure x-ray diffraction. We constrain the adiabatic bulk modulus to the range 2.7-5.3 GPa.

Original languageEnglish (US)
Pages (from-to)3202-3213
Number of pages12
JournalBiophysical Journal
Volume85
Issue number5
DOIs
StatePublished - Nov 2003

All Science Journal Classification (ASJC) codes

  • Biophysics

Fingerprint Dive into the research topics of 'Sound Velocity and Elasticity of Tetragonal Lysozyme Crystals by Brillouin Spectroscopy'. Together they form a unique fingerprint.

  • Cite this