Optical measurements of long-range protein vibrations

Abstract

Protein biological function depends on structural flexibility and change. From cellular communication through membrane ion channels to oxygen uptake and delivery by haemoglobin, structural changes are critical. It has been suggested that vibrations that extend through the protein play a crucial role in controlling these structural changes. While nature may utilize such long-range vibrations for optimization of biological processes, bench-top characterization of these extended structural motions for engineered biochemistry has been elusive. Here we show the first optical observation of long-range protein vibrational modes. This is achieved by orientation-sensitive terahertz near-field microscopy measurements of chicken egg white lysozyme single crystals. Underdamped modes are found to exist for frequencies 410 cm À 1 . The existence of these persisting motions indicates that damping and intermode coupling are weaker than previously assumed. The methodology developed permits protein engineering based on dynamical network optimization.

Perspective: Watching low-frequency vibrations of water in biomolecular recognition by THz spectroscopy

“…[51][52][53]28 For all antifreeze active proteins with their mutants, a long-range effect on the hydration water dynamics (i.e., a retardation was found). The dynamical "hydration funnel" could extend over five hydration shells, indicative of a perturbed water network near the protein (see Fig.…”

“…26,27 Recently, Markelz et al introduced a new detection schema to selectively monitor collective protein vibrations. 28 By probing the interaction of an oriented single crystal with linear polarized THz light, her group could separate the THz response of the aligned protein from the response of the randomly oriented water frozen in the crystal experimentally. Modes of the lysozyme single protein crystals at frequencies >10 cm −1 were observed by polarization-sensitive terahertz near-field microscopy.…”

Seeing Cell Biology with the Eyes of Physics

“…A single protein can be considered as a phase-resonant vibrating system [25]. Near terahertz field microscopy has captured protein vibrations, tiny motions essential for Life [25].…”

Terahertz optical measurements of correlated motions with possible allosteric function

“…Measurements have been performed on tetragonal HEWL crystals for fully hydrated and partially hydrated crystals (Acbas et al 2014). The large optical density of the protein crystals along with the aspect ratio of approximately 1 resulted in a preferred crystal size of≤300 μm, which significantly simplifies the crystal growth and makes the technique accessible to many proteins.…”

“…In this paper we discuss the challenges of characterizing collective vibrations and our development of an optical technique, namely, crystal anisotropy terahertz microscopy (CATM), which reveals the collective vibrations. The technique has the potential for structurally characterizing the collective motions (Acbas et al 2014). We also discuss the fundamental challenge of the dense spectrum and different possible strategies to decompose the spectrum in terms of the nature of the structural motions.…”