%0 Journal Article %J Nature Communications %D 2014 %T Optical measurements of long-range protein vibrations %A Acbas, G. %A Niessen, K. A. %A Snell, E. H. %A Markelz, A. G. %K absorption %K crystals %K dynamics %K frequency raman-spectra %K hydration %K lysozyme %K motions %K Science & Technology - Other Topics %K sensitivity %K simulations %K spectroscopy %X

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 >10 cm(-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.

%B Nature Communications %V 5 %P 7 %8 Jan %@ 2041-1723 %G English %9 Article %M WOS:000331084200018 %] 3076 %R https://doi.org/10.1038/ncomms4076 %0 Conference Proceedings %B Ultrafast Phenomena and Nanophotonics Xvii %D 2013 %T Measuring phonons in protein crystals %A Acbas, G. %A Niessen, K. A. %A George, D. K. %A Snell, E. %A Markelz, A. G. %E Betz, M. %E Elezzabi, A. Y. %E Song, J. J. %E Tsen, K. T. %K correlated motions %K dynamics %K mode %K molecular crystals %K molecular vibrations %K normal modes %K phonons %K protein dynamics %K spectroscopy %K Terahertz %X

Using Terahertz near field microscopy we find orientation dependent narrow band absorption features for lysozyme crystals. Here we discuss identification of protein collective modes associated with the observed features. Using normal mode calculations we find good agreement with several of the measured features, suggesting that the modes arise from internal molecular motions and not crystal phonons. Such internal modes have been associated with protein function.

%B Ultrafast Phenomena and Nanophotonics Xvii %S Proceedings of SPIE %I Spie-Int Soc Optical Engineering %C Bellingham %V 8623 %@ 978-0-8194-9392-7 %G English %M WOS:000322829300003 %R https://doi.org/10.1117/12.2006275 %0 Conference Proceedings %B 2012 37th International Conference on Infrared, Millimeter, and Terahertz Waves %D 2012 %T Orientation Sensitive Terahertz Resonances Observed in Protein Crystals %A Acbas, G. %A Snell, E. %A Markelz, A. G. %K dynamics %K mode %X

A method is presented for measuring anisotropic THz response for small crystals, Crystal Anisotropy Terahertz Microscopy (CATM). Sucrose CATM measurements find the expected anisotropic phonon resonances. CATM measurements of protein crystals find the expected broadband water absorption is suppressed and strong orientation and hydration dependent resonant features.

%B 2012 37th International Conference on Infrared, Millimeter, and Terahertz Waves %S International Conference on Infrared Millimeter and Terahertz Waves %I Ieee %C New York %@ 978-1-4673-1597-5 %G English %M WOS:000330301800120 %R https://doi.org/10.1109/IRMMW-THz.2012.6380168