02497nas a2200193 4500008004100000245012000041210006900161260001200230300001200242490000600254520187500260100001302135700002102148700001902169700002002188700001502208700001802223856006202241 2021 eng d00aNear-Field Stationary Sample Terahertz Spectroscopic Polarimetry for Biomolecular Structural Dynamics Determination0 aNearField Stationary Sample Terahertz Spectroscopic Polarimetry  c02/2021 a658-6680 v83 a

THz polarimetry on environmentally sensitive and microscopic samples can provide unique insight into underlying mechanisms of complex phenomena. For example, near-field THz anisotropic absorption successfully isolated protein structural vibrations which are connected to biological function. However, to determine how these vibrations impact function requires high throughput measurements of these complex systems, which is challenged by the need for near field detection, sample environmental control and full polarization variation. Stationary sample anisotropic terahertz spectroscopy (SSATS) and near-field stationary sample anisotropic terahertz microscopy (SSATM) have been proposed using synchronous control of THz and electro optic probe polarizations along an iso-response curve. Here we realize these techniques through robust control and calibration of the THz and NIR polarization states. Both methods rapidly measure the linear dichroism in the far field and near field. Validation measurements using standard birefringent sucrose single crystals found the crystal orientation can be determined by scanning the reference polarization and the synchronous pump–probe polarization settings can be optimized to eliminate artifacts. SSATM is then used to determine spectral reproducibility and dehydration effects for a series of chicken egg white lysozyme samples. Reproducible anisotropic absorbance bands are found at about 30, 44, 55, and 62 cm–1. These bands initially sharpen with slow dehydration, similar to the increase in resolution achieved in X-ray crystallographic protein structure determination. The SSATM technique confirms the reliability of anisotropic absorption characterization of protein intramolecular vibrations and opens an avenue for rapid determination of how these long-range dynamics affect biological function.

1 aDeng, Y.1 aMcKinney, J., A.1 aGeorge, D., K.1 aNiessen, K., A.1 aSharma, A.1 aMarkelz, A.G. uhttps://pubs.acs.org/doi/abs/10.1021/acsphotonics.0c0187601859nas a2200241 4500008004500000020001400045245011000059210006900169260000800238300001400246490000800260520114300268653001501411100002101426700001501447700001601462700001301478700001901491700002201510700001601532700002001548856004901568 2020 Engldsh  a0006-349500aEvidence of Intramolecular Structural Stabilization in Light Activated State of Orange Carotenoid Protein0 aEvidence of Intramolecular Structural Stabilization in Light Act cFeb a208A-208A0 v1183 a

Orange carotenoid protein (OCP) controls efficiency of the light harvesting antenna, the phycobilisome (PBS), in diverse cyanobacteria and prevents oxidative damage. It is the only known photoactive protein that uses a carotenoid, canthaxanthin, as its chromophore. The structure of OCP consists of two globular domains, connected by an unstructured loop, that forms a hydrophobic pocket for the carotenoid. In low light, canthaxanthin bound OCP is inactive and appears orange. Illumination by strong light results in an active state that interacts with the PBS to induce fluorescence quenching, a red appearance and conformational changes that include a 12Å shift by canthaxanthin into the N-terminal domain. Terahertz (THz) dynamical transition measurements and anisotropic terahertz microscopy are used to measure the intramolecular structural dynamics in the inactive and active states, which can be induced by photoexcitation or chaotropic salts. The measurements indicate that the active state has a decrease in structural flexibility, which may be related to enhanced interactions with the PBS.

10aBiophysics1 aMcKinney, J., A.1 aSharma, A.1 aCrossen, K.1 aDeng, Y.1 aGeorge, D., K.1 aLechno-Yossef, S.1 aKerfeld, C.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/25300443nas a2200157 4500008004100000245004800041210004000089490000800129100001500137700001900152700001600171700001700187700001600204700001600220856004900236 2020 eng d00aIs the Protein Dynamical Transition useful?0 aProtein Dynamical Transition useful0 v1181 aSharma, A.1 aGeorge, D., K.1 aCrossen, K.1 aMcKinney, J.1 aKerfeld, C.1 aMarkelz, A. uhttps://markelz.physics.buffalo.edu/node/28201881nas a2200181 4500008004100000245009900041210006900140260001600209520131100225100001701536700001501553700001301568700001501581700002201596700001601618700001601634856004901650 2020 eng d00aStabilization of Terahertz Vibrational Modes in Illuminated Orange Carotenoid Protein Crystals0 aStabilization of Terahertz Vibrational Modes in Illuminated Oran aBuffalo, NY3 a

Orange carotenoid protein (OCP) controls efficiency of the phycobilisome (PBS), the light harvesting antenna in cyanobacteria, to prevent oxidative damage. The OCP switches from resting state to photo protective state with intense blue light illumination. Questions persist as to why OCPR interaction increases with the PBS over that with the OCPO. Here we examine the role of long-range intramolecular vibrations within OCP. Using Stationary Sample Anisotropic Terahertz Microscopy (SSATM) we measure changes in the intramolecular vibrations with photo switching. We report the first observation of switching in the intramolecular vibrations with photoexcitation. Results suggest that there is a stiffening of the molecule in the photo protective state. This increase in structural stability may enhance the interaction with the PBS change in OCP interaction with PBS. In low light, carotenoid bound OCP appears orange (OCP o ) and is inactive. Illumination by strong light converts OCP to the active, red (OCPR) state, which interacts with the PBS. A comparison of anisotropic THz microscopy measurements of dark adapted (OCP o ) and illuminated OCP crystals indicate differences in their vibrational modes that may be important for OCP-PBS interactions.

1 aMcKinney, J.1 aSharma, A.1 aDeng, Y.1 aGeorge, D.1 aLechno-Yossef, S.1 aKerfeld, C.1 aMarkelz, A. uhttps://markelz.physics.buffalo.edu/node/54401100nas a2200169 4500008004500000020002200045245011300067210006900180260001900249520052500268100001700793700001700810700001500827700001900842700002000861856004900881 2019 Engldsh  a978-1-5386-8285-200aAnisotropic Terahertz Microscopy of Protein Collective Vibrations: Crystal Symmetry and Hydration Dependence0 aAnisotropic Terahertz Microscopy of Protein Collective Vibration aNew YorkbIeee3 a

A stationary sample anisotropic terahertz microscopy technique is used to characterize the intramolecular vibrations for lysozyme. Tetragonal and triclinic crystals are compared. We find excellent reproducibility within a single crystal symmetry group. Several resonant bands are present for both symmetry groups, indicating they originate with the intramolecular vibrations and not crystal lattice phonons. Bands become more pronounced and higher frequency resonant bands begin to emerge with slight dehydration.

1 aMcKinney, J.1 aDeng, Y., T.1 aSharma, A.1 aGeorge, D., K.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/23500501nas a2200145 4500008004100000245011200041210006900153490001200222100001100234700001300245700001300258700001500271700001600286856005300302 2018 eng d00aMeasuring Protein Intramolecular Dynamics with Terahertz Light: Functional Changes and Relevance to Biology0 aMeasuring Protein Intramolecular Dynamics with Terahertz Light F0 vH50.0011 aXu, M.1 aDeng, Y.1 aLuck, C.1 aSharma, A.1 aMarkelz, A. uhttp://meetings.aps.org/link/BAPS.2018.MAR.H50.1