The solid state photo-CIDNP effect

Photochemically induced dynamic nuclear polarization (photo-CIDNP) is non-Boltzmann nuclear magnetization which can be observed by magic angle spinning NMR spectroscopy as enhanced absorptive or emissive signals. In solids, photo-CIDNP has been observed since its discovery in 1994 in various photosynthetic reaction centers. In natural photosynthetic charge separation, electron-electron interactions are fine-tuned to lead to highly efficient electron transfer. Nanosecond laser-flash photo-CIDNP magic-angle spinning NMR allows for determination of the nuclear polarizations and hyperfine interactions with atomic selectivity and with a resolution of a few microseconds. The build-up of nuclear polarization in reaction centers of Rhodobacter sphaeroides is found to depend on the presence and lifetimes of the molecular triplet states of the donor and carotenoid. Time-resolved 13C photo-CIDNP MAS NMR spectroscopy is used to map the electronic structure of the donor. In the dark state, maximum electron density is localized in the center of the special pair. In contrast, in the light state, the maximum of the electron spin density is localized at the periphery of the two cofactors. The balance of electron spin density between the two bacteriochlorophyll cofactors is shifted in favor of the L branch of the protein by the ratio of 7:3. We show that the asymmetry is induced by both geometric differences between the two cofactors and non-covalent interactions with the protein.EMBO, NWO, Spectraphysics-Newport, Bruker BiospinUBL - phd migration 201

Efficient resonance assignment of proteins in MAS NMR by simultaneous intra- and inter-residue 3D correlation spectroscopy

Resonance assignment is the first step in NMR structure determination. For magic angle spinning NMR, this is typically achieved with a set of heteronuclear correlation experiments (NCaCX, NCOCX, CONCa) that utilize SPECIFIC-CP [superscript 15]N–[superscript 13]C transfers. However, the SPECIFIC-CP transfer efficiency is often compromised by molecular dynamics and probe performance. Here we show that one-bond ZF-TEDOR [superscript 15]N– [superscript 13]C transfers provide simultaneous NCO and NCa correlations with at least as much sensitivity as SPECIFIC-CP for some non-crystalline samples. Furthermore, a 3D ZF-TEDOR-CC experiment provides heteronuclear sidechain correlations and robustness with respect to proton decoupling and radiofrequency power instabilities. We demonstrate transfer efficiencies and connectivities by application of 3D ZF-TEDOR-DARR to a model microcrystalline protein, GB1, and a less ideal system, GvpA in intact gas vesicles.National Institutes of Health. National Institute for Biomedical Imaging and Bioengineering (Grant EB-001960)National Institutes of Health. National Institute for Biomedical Imaging and Bioengineering (Grant EB-002926)National Institutes of Health. National Institute for Biomedical Imaging and Bioengineering (Grant EB-001035

Action Spectroscopy on Dense Samples of Photosynthetic Reaction Centers of Rhodobacter sphaeroides WT Based on Nanosecond Laser-Flash 13C Photo-CIDNP MAS NMR

Photochemically induced dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance (photo-CIDNP MAS NMR) allows for the investigation of the electronic structure of the photochemical machinery of photosynthetic reaction centers (RCs) at atomic resolution. For such experiments, either continuous radiation from white xenon lamps or green laser pulses are applied to optically dense samples. In order to explore their optical properties, optically thick samples of isolated and quinone-removed RCs of the purple bacteria of Rhodobacter sphaeroides wild type are studied by nanosecond laser-flash 13C photo-CIDNP MAS NMR using excitation wavelengths between 720 and 940 nm. Action spectra of both the transient nuclear polarization as well as the nuclear hyperpolarization, remaining in the electronic ground state at the end of the photocycle, are obtained. It is shown that the signal intensity is limited by the amount of accessible RCs and that the different mechanisms of the photo-CIDNP production rely on the same photophysical origin, which is the photocycle induced by one single photon

Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy

In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a [superscript 13]C-Urea sample using this gyrotron.National Institutes of Health (U.S.) (Grant EB002804)National Institutes of Health (U.S.) (Grant EB003151)National Institutes of Health (U.S.) (Grant EB002026)National Institutes of Health (U.S.) (Grant EB001960)National Institutes of Health (U.S.) (Grant EB001035)National Institutes of Health (U.S.) (Grant EB001965)National Institutes of Health (U.S.) (Grant EB004866

The Grizzly, November 5, 1982

Clinic Offered for Ski-Bums • Outstanding Choral Students Chosen • U.C. Poses for Posterity • Letters to the Editor: Greeks Piqued • USGA Notes • President\u27s Corner • Ropes and Chains or Can You Eat Plasterboard? • Protheatre Presents Comedy at its Best • The Messiah is Coming! • The World\u27s Largest Picture at Ursinus: Get Yours Now! • Take That, West Chester! • Soccer Season Ends With Win Over Widener • Bear Pack Waltzes to Victory • Bears Battle But Lose War • Lady Bears Dominatehttps://digitalcommons.ursinus.edu/grizzlynews/1087/thumbnail.jp

The Grizzly, October 29, 1982

Violence in Girls\u27 Dorm: Collegian Suspended After Fight • Managerial Communications Workshop Offered to Ursinus Students • Ursinus College Bowl Returns • Hazard and His Heroes to Rock Helfferich Hall • Letters to the Editor: Making Mountains Out of Food Hills; Please Live in Dorms • President\u27s Corner • Registration: A Game of Luck, Chance and Daring • Lewis on Wall Street • USGA Plans Activities • Sports Profile: Overcoming Adversity Beener-style • Diplomats Dump the Grizzlies • Booters Bearly Beat Muhlenberg • Lady Bears Drop One to Rival West Chesterhttps://digitalcommons.ursinus.edu/grizzlynews/1086/thumbnail.jp

The Grizzly, October 15, 1982

Students for Peace and Progress Get Started • Homecoming 1982 • Annual Parents Day a Success • Letters to the Editor • Opinion: Sorority Rushing Needs Revision • Lantern Format Undecided • Dance-a-Thon for Lupus • Japan: Big and Real • New Art at Myrin • Bear Booters Win Three • Now Hold it Just a Minute! • Grizzlies Win Third Straight • X-Country Wins • Penn Blasts Lady Bears 3-0https://digitalcommons.ursinus.edu/grizzlynews/1084/thumbnail.jp

The Grizzly, March 25, 1983

New Editors Elected: Romer, Hong, Pasekoff Named • Superstars Tournament Needs Participants • DuPont Gives Third Consecutive Chemistry Grant • The A\u27s Come to UC • Third Annual Special Olympics This Weekend • Summer in Japan • Folk Singers at Bomberger • Letters to the Editor: An Epilogue to Zeta Chi • USGA Holds Election • USGA Notes • Voight at Bat • 13 Spend Break in Quebec • To Hell With the USFL • College Bowl Goes to Maryland • 1983 Room Selection Procedure • Bear\u27s Den Replaces Cafe International • Cycling Marathon: Ride for Your Life • Men\u27s Lacrosse Slow Getting Started • Men\u27s and Women\u27s Track Win Openershttps://digitalcommons.ursinus.edu/grizzlynews/1097/thumbnail.jp

Observation of the solid-state photo-CIDNP effect in entire cells of cyanobacteria Synechocystis

Cyanobacteria are widely used as model organism of oxygenic photosynthesis due to being the simplest photosynthetic organisms containing both photosystem I and II (PSI and PSII). Photochemically induced dynamic nuclear polarization (photo-CIDNP) 13C magic-angle spinning (MAS) NMR is a powerful tool in understanding the photosynthesis machinery down to atomic level. Combined with selective isotope enrichment this technique has now opened the door to study primary charge separation in whole living cells. Here, we present the first photo-CIDNP observed in whole cells of the cyanobacterium Synechocystis

Nanosecond-Flash N-15 Photo-CIDNP MAS NMR on reaction centers of Rhodobacter sphaeroides R26

Solid state NMR/Biophysical Organic ChemistryBiological and Soft Matter Physic