Protein Intramolecular Motions with Deuteration and Inhibitor Binding Dependence*

Protein collective vibrations dynamically sample structural configurations enabling conformational change [1]. Recently these vibrations have been isolated by their direction of motion using anisotropic terahertz microscopy [2]. To assign structural displacements with the observed resonant absorption bands, we measure their changes with deuteration and inhibitor (3NAG) binding for lysozyme using triclinic crystals and compare these measurements to normal mode ensemble analysis (NMEA) [2]. The sample’s P1 crystal symmetry and quality were confirmed by X-ray after THz measurements with a = 28.5 Å, b = 32.7 Å, c = 35.1 Å, α = 88.2°, β = 108.9°, γ = 111.9°. The protonated, deuterated and 3NAG-bound triclinic crystals were measured using a new technique: ideal polarization varying anisotropic Terahertz microscopy. We compare the relative frequency shifts of the measured protonated and deuterated protein vibrations, and changes with inhibitor binding dependence to the calculated spectra averaged over >500 starting structures to make tentative assignments.
1. Mahajan, S. and Y.-H. Sanejouand, Arch. Biochem. Biophys., 2015. 567: p. 59-65.
2. Niessen, K.A., et al., Biophys. J., 2017. 112(5): p. 933-942.