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Nevzorov AA, Marek A, Milikisiyants S, Smirnov AI. High-frequency high-power DNP/EPR spectrometer operating at 7 T magnetic field. J Magn Reson 2024; 362:107677. [PMID: 38631171 DOI: 10.1016/j.jmr.2024.107677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/26/2024] [Accepted: 04/09/2024] [Indexed: 04/19/2024]
Abstract
One of the most essential prerequisites for the development of pulse Dynamic Nuclear Polarization (DNP) is the ability to generate high-power coherent mm-wave pulses at the electron precession frequencies corresponding to the magnetic fields of modern high-resolution NMR spectrometers. As a major step towards achieving this goal, an Extended Interaction Klystron (EIK) pulse amplifier custom-built by the Communications and Power Industries, Inc. and producing up to 140 W at 197.8 GHz, was integrated with in-house built NMR/DNP/EPR spectrometer operating at 7 T magnetic field. The spectrometer employs a Thomas Keating, Ltd. quasioptical bridge to direct mm-waves into a homebuilt DNP probe incorporating photonic bandgap (PBG) resonators to further boost electronic B1e fields. Three-pulse electron spin echo nutation experiments were employed to characterize the B1e fields at the sample by operating the homodyne 198 GHz bridge in an induction mode. Room-temperature experiments with a single-crystal high-pressure, high-temperature (HPHT) diamond and a polystyrene film doped with BDPA radical yielded < 9 ns π/2 pulses at ca. 50 W specified EIK output at the corresponding resonance frequencies and the PBG resonator quality factor of Q≈300. DNP experiments carried out in a "gated" mode by supplying 20 μs mm-wave pulses every 1 ms yielded 13C solid-effect DNP with gains up to 20 for the polystyrene-BDPA sample at natural 13C abundance. For a single-crystal HPHT diamond, the gated DNP mode yielded almost the same 13C enhancement as a low-power continuous wave (CW) mode at 0.4 W, whereas no DNP effect was observed for the BDPA/polystyrene sample in the latter case. To illustrate the versatility of our upgraded DNP spectrometer, room-temperature Overhauser DNP enhancements of 7-14 for 31P NMR signal were demonstrated using a liquid droplet of 1 M tri-phenyl phosphine co-dissolved with 100 mM of BDPA in toluene‑d8.
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Affiliation(s)
- Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, US.
| | - Antonin Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, US
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, US
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, US.
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2
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Nunn N, Milikisiyants S, Torelli MD, Monge R, Delord T, Shames AI, Meriles CA, Ajoy A, Smirnov AI, Shenderova OA. Optical and electronic spin properties of fluorescent micro- and nanodiamonds upon prolonged ultrahigh-temperature annealing. J Vac Sci Technol B Nanotechnol Microelectron 2023; 41:042206. [PMID: 37387792 PMCID: PMC10306410 DOI: 10.1116/6.0002797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/08/2023] [Indexed: 07/01/2023]
Abstract
High-temperature annealing is a promising but still mainly unexplored method for enhancing spin properties of negatively charged nitrogen-vacancy (NV) centers in diamond particles. After high-energy irradiation, the formation of NV centers in diamond particles is typically accomplished via annealing at temperatures in the range of 800-900 °C for 1-2 h to promote vacancy diffusion. Here, we investigate the effects of conventional annealing (900 °C for 2 h) against annealing at a much higher temperature of 1600 °C for the same annealing duration for particles ranging in size from 100 nm to 15 μm using electron paramagnetic resonance and optical characterization. At this high temperature, the vacancy-assisted diffusion of nitrogen can occur. Previously, the annealing of diamond particles at this temperature was performed over short time scales because of concerns of particle graphitization. Our results demonstrate that particles that survive this prolonged 1600 °C annealing show increased NV T1 and T2 electron spin relaxation times in 1 and 15 μm particles, due to the removal of fast relaxing spins. Additionally, this high-temperature annealing also boosts magnetically induced fluorescence contrast of NV centers for particle sizes ranging from 100 nm to 15 μm. At the same time, the content of NV centers is decreased fewfold and reaches a level of <0.5 ppm. The results provide guidance for future studies and the optimization of high-temperature annealing of fluorescent diamond particles for applications relying on the spin properties of NV centers in the host crystals.
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Affiliation(s)
- Nicholas Nunn
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607
| | | | | | - Tom Delord
- Department of Physics, CUNY—City College of New York, New York, New York 10031
| | - Alexander I. Shames
- Department of Physics, Ben Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | | | | | - Alex I. Smirnov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607
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3
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Milikisiyants S, Marek A, Voinov MA, Kern JF, Smirnov AI. Nanopore-enabled macroscopic alignment of 700 kDa membrane protein complex: Characterization by pulsed EPR. Biophys J 2023; 122:550a. [PMID: 36784854 DOI: 10.1016/j.bpj.2022.11.2912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | - Antonin Marek
- Chemistry, North Carolina State University, Raleigh, NC, USA
| | - Maxim A Voinov
- Chemistry, North Carolina State University, Raleigh, NC, USA
| | - Jan F Kern
- Molecular Biophysics, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Alex I Smirnov
- Chemistry, North Carolina State University, Raleigh, NC, USA
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4
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Saikia N, Yanez-Orozco IS, Qiu R, Hao P, Milikisiyants S, Ou E, Hamilton GL, Weninger KR, Smirnova TI, Sanabria H, Ding F. Integrative structural dynamics probing of the conformational heterogeneity in synaptosomal-associated protein 25. Cell Rep Phys Sci 2021; 2:100616. [PMID: 34888535 PMCID: PMC8654206 DOI: 10.1016/j.xcrp.2021.100616] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
SNAP-25 (synaptosomal-associated protein of 25 kDa) is a prototypical intrinsically disordered protein (IDP) that is unstructured by itself but forms coiled-coil helices in the SNARE complex. With high conformational heterogeneity, detailed structural dynamics of unbound SNAP-25 remain elusive. Here, we report an integrative method to probe the structural dynamics of SNAP-25 by combining replica-exchange discrete molecular dynamics (rxDMD) simulations and label-based experiments at ensemble and single-molecule levels. The rxDMD simulations systematically characterize the coil-to-molten globular transition and reconstruct structural ensemble consistent with prior ensemble experiments. Label-based experiments using Förster resonance energy transfer and double electron-electron resonance further probe the conformational dynamics of SNAP-25. Agreements between simulations and experiments under both ensemble and single-molecule conditions allow us to assign specific helix-coil transitions in SNAP-25 that occur in submillisecond timescales and potentially play a vital role in forming the SNARE complex. We expect that this integrative approach may help further our understanding of IDPs.
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Affiliation(s)
- Nabanita Saikia
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
- Department of Chemistry, Navajo Technical University, Chinle, AZ 86503, USA
| | | | - Ruoyi Qiu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Pengyu Hao
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Erkang Ou
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - George L. Hamilton
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Keith R. Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Tatyana I. Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
- Lead contact
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5
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Nevzorov AA, Marek A, Milikisiyants S, Smirnov AI. Characterization of photonic band resonators for DNP NMR of thin film samples at 7 T magnetic field. J Magn Reson 2021; 323:106893. [PMID: 33418455 PMCID: PMC8362290 DOI: 10.1016/j.jmr.2020.106893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Polarization of nuclear spins via Dynamic Nuclear Polarization (DNP) relies on generating sufficiently high mm-wave B1e fields over the sample, which could be achieved by developing suitable resonance structures. Recently, we have introduced one-dimensional photonic band gap (1D PBG) resonators for DNP and reported on prototype devices operating at ca. 200 GHz electron resonance frequency. Here we systematically compare the performance of five (5) PBG resonators constructed from various alternating dielectric layers by monitoring the DNP effect on natural-abundance 13C spins in synthetic diamond microparticles embedded into a commercial polyester-based lapping film of just 3 mil (76 μm) thickness. An odd-numbered configuration of dielectric layers for 1D PBG resonator was introduced to achieve further B1e enhancements. Among the PBG configurations tested, combinations of high-ε perovskite LiTaO3 together with AlN as well as AlN with optical quartz wafers have resulted in ca. 40 to over 50- fold gains in the average mm-wave power over the sample vs. the mirror-only configuration. The results are rationalized in terms of the electromagnetic energy distribution inside the resonators obtained analytically and from COMSOL simulations. It was found that average of B1e2 over the sample strongly depends on the arrangement of the dielectric layers that are the closest to the sample, which favors odd-numbered PBG resonator configurations for their use in DNP.
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Affiliation(s)
- Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
| | - Antonin Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
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6
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Chestnut MM, Milikisiyants S, Chatterjee R, Kern J, Smirnov AI. Electronic Structure of the Primary Electron Donor P700+• in Photosystem I Studied by Multifrequency HYSCORE Spectroscopy at X- and Q-Band. J Phys Chem B 2021; 125:36-48. [PMID: 33356277 DOI: 10.1021/acs.jpcb.0c09000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The primary electron donor P700 of the photosystem I (PSI) is a heterodimer consisting of two chlorophyll molecules. A series of electron-transfer events immediately following the initial light excitation leads to a stabilization of the positive charge by its cation radical form, P700+•. The electronic structure of P700+• and, in particular, its asymmetry with respect to the two chlorophyll monomers is of fundamental interest and is not fully understood up to this date. Here, we apply multifrequency X- (9 GHz) and Q-band (35 GHz) hyperfine sublevel correlation (HYSCORE) spectroscopy to investigate the electron spin density distribution in the cation radical P700+• of PSI from a thermophilic cyanobacterium Thermosynechococcus elongatus. Six 14N and two 1H distinct nuclei have been resolved in the HYSCORE spectra and parameters of the corresponding nuclear hyperfine and quadrupolar hyperfine interactions were obtained by combining the analysis of HYSCORE spectral features with direct numerical simulations. Based on a close similarity of the nuclear quadrupole tensor parameters, all of the resolved 14N nuclei were assigned to six out of total eight available pyrrole ring nitrogen atoms (i.e., four in each of the chlorophylls), providing direct evidence of spin density delocalization over the both monomers in the heterodimer. Using the obtained experimental values of the 14N electron-nuclear hyperfine interaction parameters, the upper limit of the electron spin density asymmetry parameter is estimated as RA/Bupper = 7.7 ± 0.5, while a tentative assignment of 14N observed in the HYSCORE spectra yields RB/A = 3.1 ± 0.5.
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Affiliation(s)
- Melanie M Chestnut
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695-8204, United States
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7
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Cha L, Milikisiyants S, Davidson M, Xue S, Smirnova T, Smirnov A, Guo Y, Chang WC. Alternative Reactivity of Leucine 5-Hydroxylase Using an Olefin-Containing Substrate to Construct a Substituted Piperidine Ring. Biochemistry 2020; 59:1961-1965. [PMID: 32401494 DOI: 10.1021/acs.biochem.0c00289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Applying enzymatic reactions to produce useful molecules is a central focus of chemical biology. Iron and 2-oxoglutarate (Fe/2OG) enzymes are found in all kingdoms of life and catalyze a broad array of oxidative transformations. Herein, we demonstrate that the activity of an Fe/2OG enzyme can be redirected when changing the targeted carbon hybridization from sp3 to sp2. During leucine 5-hydroxylase catalysis, installation of an olefin group onto the substrate redirects the Fe(IV)-oxo species reactivity from hydroxylation to asymmetric epoxidation. The resulting epoxide subsequently undergoes intramolecular cyclization to form the substituted piperidine, 2S,5S-hydroxypipecolic acid.
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Affiliation(s)
- Lide Cha
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Madison Davidson
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Shan Xue
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Tatyana Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Alex Smirnov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Wei-Chen Chang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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8
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Voinov MA, Milikisiyants S, Perelygin V, Chestnut MM, Munro R, Brown LS, Ladizhansky V, Smirnov AI. Rhodopsin Oligomerization in Synthetic Lipid Bilayers and Native Cellular Membranes as Studied by DEER of a Spin-labeled Retinal Analog. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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9
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Milikisiyants S, Voinov MA, Marek A, Jafarabadi M, Liu J, Han R, Wang S, Smirnov AI. Enhancing sensitivity of Double Electron-Electron Resonance (DEER) by using Relaxation-Optimized Acquisition Length Distribution (RELOAD) scheme. J Magn Reson 2019; 298:115-126. [PMID: 30544015 PMCID: PMC6894391 DOI: 10.1016/j.jmr.2018.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/02/2018] [Accepted: 12/04/2018] [Indexed: 05/05/2023]
Abstract
Over the past decades pulsed electron-electron double resonance (PELDOR), often called double electron-electron resonance (DEER), became one of the major spectroscopic tools for measurements of nanometer-scale distances and distance distributions in non-crystalline biological and chemical systems. The method is based on detecting the amplitude of the primary (3-pulse DEER) or refocused (4-pulse DEER) spin echo for the so-called "observer" spins when the other spins coupled to the former by a dipolar interaction are flipped by a "pump" pulse at another EPR frequency. While the timing of the pump pulse is varied in steps, the positions of the observer pulses are typically fixed. For such a detection scheme the total length of the observer pulse train and the electron spin memory time determine the amplitude of the detected echo signal. Usually, the distance range considerations in DEER experiments dictate the total length of the observer pulse train to exceed the phase memory time by a factor of few and this leads to a dramatic loss of the signal-to-noise ratio (SNR). While the acquisition of the DEER signal seems to be irrational under such conditions, it is currently the preferred way to conduct DEER because of an effective filtering out of all other unwanted interactions. Here we propose a novel albeit simple approach to improve DEER sensitivity and decrease data acquisition time by introducing the signal acquisition scheme based on RELaxation Optimized Acquisition (Length) Distribution (DEER-RELOAD). In DEER-RELOAD the dipolar phase evolution signal is acquired in multiple segments in which the observer pulses are fixed at the positions to optimize SNR just for that specific segment. The length of the segment is chosen to maximize the signal acquisition efficiency according the phase relaxation properties of the spin system. The total DEER trace is then obtained by "stitching" the multiple segments into a one continuous trace. The utility of the DEER-RELOAD acquisition scheme has been demonstrated on an example of the standard 4-pulse DEER sequence applied to two membrane protein complexes labeled with nitroxides. While theoretical gains from the DEER-RELOAD scheme increase with the number of stitched segments, in practice, even dividing the acquisition of the DEER trace into two segments may improve SNR by a factor of >3, as it has been demonstrated for one of these two membrane proteins.
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Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Maxim A Voinov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Antonin Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Morteza Jafarabadi
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Jing Liu
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Rong Han
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Shenlin Wang
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Alex I Smirnov
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China.
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Nevzorov AA, Milikisiyants S, Marek AN, Smirnov AI. Multi-resonant photonic band-gap/saddle coil DNP probehead for static solid state NMR of microliter volume samples. J Magn Reson 2018; 297:113-123. [PMID: 30380458 PMCID: PMC6894392 DOI: 10.1016/j.jmr.2018.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/18/2018] [Accepted: 10/20/2018] [Indexed: 05/04/2023]
Abstract
The most critical condition for performing Dynamic Nuclear Polarization (DNP) NMR experiments is achieving sufficiently high electronic B1e fields over the sample at the matched EPR frequencies, which for modern high-resolution NMR instruments fall into the millimeter wave (mmW) range. Typically, mmWs are generated by powerful gyrotrons and/or extended interaction klystrons (EIKs) sources and then focused onto the sample by dielectric lenses. However, further development of DNP methods including new DNP pulse sequences may require B1e fields higher than one could achieve with the current mmW technology. In order to address the challenge of significantly enhancing the mmW field at the sample, we have constructed and tested one-dimensional photonic band-gap (PBG) mmW resonator that was incorporated inside a double-tuned radiofrequency (rf) NMR saddle coil. The photonic crystal is formed by stacking ceramic discs with alternating high and low dielectric constants and thicknesses of λ/4 or 3λ/4, where λ is the wavelength of the incident mmW field in the corresponding dielectric material. When the mmW frequency is within the band gap of the photonic crystal, a defect created in the middle of the crystal confines the mmW energy, thus forming a resonant structure. An aluminum mirror in the middle of the defect has been used to substitute one-half of the structure with its mirror image in order to reduce the resonator size and simplify its tuning. The latter is achieved by adjusting the width of the defect by moving the aluminum mirror with respect to the dielectric stack using a gear mechanism. The 1D PBG resonator was the key element for constructing a multi-resonant integrated DNP/NMR probehead operating at 190-199 GHz EPR/300 MHz 1H/75.5 MHz 13C NMR frequencies. Initial tests of the multi-resonant DNP/NMR probehead were carried out using a quasioptical mmW bridge and a Bruker Biospin Avance II spectrometer equipped with a standard Bruker 7 T wide-bore 89 mm magnet parked at 300.13 MHz 1H NMR frequency. The mmW bridge built with all solid-state active components allows for the frequency tuning between ca. 190 and ca. 199 GHz with the output power up to 27 dBm (0.5 W) at 192 GHz and up to 23 dBm (0.2 W) at 197.5 GHz. Room temperature DNP experiments with a synthetic single crystal high-pressure high-temperature (HPHT) diamond (0.3 × 0.3 × 3.0 mm3) demonstrated dramatic 1500-fold enhancement of 13C natural abundance NMR signal at full incident mmW power. Significant 13C DNP enhancement (of about 90) have been obtained at incident mmW powers of as low as <100 μW. Further tests of the resonator performance have been carried out with a thin (ca. 100 μm thickness) composite polystyrene-microdiamond film by controlling the average mmW power at the optimal DNP conditions via a gated mode of operation. From these experiments, the PBG resonator with loaded Q ≃ 250 and finesse F≈75 provides up to 12-fold or 11 db gain in the average mmW power vs. the non-resonant probehead configuration employing only a reflective mirror.
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Affiliation(s)
- Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
| | - Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States
| | - Antonin N Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
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11
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Yu CP, Tang Y, Cha L, Milikisiyants S, Smirnova TI, Smirnov AI, Guo Y, Chang WC. Elucidating the Reaction Pathway of Decarboxylation-Assisted Olefination Catalyzed by a Mononuclear Non-Heme Iron Enzyme. J Am Chem Soc 2018; 140:15190-15193. [PMID: 30376630 DOI: 10.1021/jacs.8b10077] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Installation of olefins into molecules is a key transformation in organic synthesis. The recently discovered decarboxylation-assisted olefination in the biosynthesis of rhabduscin by a mononuclear non-heme iron enzyme ( P.IsnB) represents a novel approach in olefin construction. This method is commonly employed in natural product biosynthesis. Herein, we demonstrate that a ferryl intermediate is used for C-H activation at the benzylic position of the substrate. We further establish that P.IsnB reactivity can be switched from olefination to hydroxylation using electron-withdrawing groups appended on the phenyl moiety of the analogues. These experimental observations imply that a pathway involving an initial C-H activation followed by a benzylic carbocation species or by electron transfer coupled β-scission is likely utilized to complete C═C bond formation.
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Affiliation(s)
- Cheng-Ping Yu
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yijie Tang
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Lide Cha
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Sergey Milikisiyants
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Tatyana I Smirnova
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Alex I Smirnov
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
| | - Yisong Guo
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Wei-Chen Chang
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695 , United States
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12
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Milikisiyants S, Nevzorov AA, Smirnov AI. Photonic band-gap resonators for high-field/high-frequency EPR of microliter-volume liquid aqueous samples. J Magn Reson 2018; 296:152-164. [PMID: 30268940 PMCID: PMC6235713 DOI: 10.1016/j.jmr.2018.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/17/2018] [Accepted: 09/19/2018] [Indexed: 05/12/2023]
Abstract
High-field EPR provides significant advantages for studying structure and dynamics of molecular systems possessing an unpaired electronic spin. However, routine use of high-field EPR in biophysical research, especially for aqueous biological samples, is still facing substantial technical difficulties stemming from high dielectric millimeter wave (mmW) losses associated with non-resonant absorption by water and other polar molecules. The strong absorbance of mmW's by water also limits the penetration depth to just fractions of mm or even less, thus making fabrication of suitable sample containers rather challenging. Here we describe a radically new line of high Q-factor mmW resonators that are based on forming lattice defects in one-dimensional photonic band-gap (PBG) structures composed of low-loss ceramic discs of λ/4 in thickness and having alternating dielectric constants. A sample (either liquid or solid) is placed within the E = 0 node of the standing mm wave confined within the defect. A resonator prototype has been built and tested at 94.3 GHz. The resonator performance is enhanced by employing ceramic nanoporous membranes as flat sample holders of controllable thickness and tunable effective dielectric constant. The experimental Q-factor of an empty resonator was ≈ 420. The Q-factor decreased slightly to ≈ 370 when loaded with a water-containing nanoporous disc of 50 μm in thickness. The resonator has been tested with a number of liquid biological samples and demonstrated about tenfold gain in concentration sensitivity vs. a high-Q cylindrical TE012-type cavity. Detailed HFSS Ansys simulations have shown that the resonator structure could be further optimized by properly choosing the thickness of the aqueous sample and employing metallized surfaces. The PBG resonator design is readily scalable to higher mmW frequencies and is capable of accommodating significantly larger sample volumes than previously achieved with either Fabry-Perot or cylindrical resonators.
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Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States
| | - Alexander A Nevzorov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695-8204, United States.
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Milikisiyants S, Voinov MA, Smirnov AI. Refocused Out-Of-Phase (ROOPh) DEER: A pulse scheme for suppressing an unmodulated background in double electron-electron resonance experiments. J Magn Reson 2018; 293:9-18. [PMID: 29800786 DOI: 10.1016/j.jmr.2018.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/12/2018] [Accepted: 05/14/2018] [Indexed: 05/24/2023]
Abstract
EPR pulsed dipolar spectroscopy (PDS) is indispensable for measurements of nm-scale distances between electronic spins in biological and other systems. While several useful modifications and pulse sequences for PDS have been developed in recent years, DEER experiments utilizing pump and observer pulses at two different frequencies remain the most popular for practical applications. One of the major drawbacks of all the available DEER approaches is the presence of a significant unmodulated fraction in the detected signal that arises from an incomplete inversion of the coupled spins by the pump pulse. The latter fraction is perceived as one of the major sources of error for the reconstructed distance distributions. We describe an alternative detection scheme - a Refocused Out-Of-Phase DEER (ROOPh-DEER) - to acquire only the modulated fraction of the dipolar DEER signal. When Zeeman splitting is small compared to the temperature, the out-of-phase magnetization components cancel each other and are not observed in 4-pulse DEER experiment. In ROOPh-DEER these components are refocused by an additional pump pulse while the in-phase component containing an unmodulated background is filtered out by a pulse at the observed frequency applied right at the position of the refocused echo. Experimental implementation of the ROOPh-DEER detection scheme requires at least three additional pulses as was demonstrated on an example of a 7-pulse sequence. The application of 7-pulse ROOPh-DEER sequence to a model biradical yielded the interspin distance of 1.94 ± 0.07 nm identical to the one obtained with the conventional 4-pulse DEER, however, without the unmodulated background present as a dominant fraction in the latter signal.
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Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Maxim A Voinov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA.
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Weninger K, Qiu R, Ou E, Milikisiyants S, Sanabria H, Smirnova TI. smFRET and DEER Distance Measurements as Applied to Disordered and Structured Proteins. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2987] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Voinov MA, Good DB, Ward ME, Milikisiyants S, Marek A, Caporini MA, Rosay M, Munro RA, Ljumovic M, Brown LS, Ladizhansky V, Smirnov AI. Cysteine-Specific Labeling of Proteins with a Nitroxide Biradical for Dynamic Nuclear Polarization NMR. J Phys Chem B 2015; 119:10180-90. [DOI: 10.1021/acs.jpcb.5b05230] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Maxim A. Voinov
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | | | | | - Sergey Milikisiyants
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Antonin Marek
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Marc A. Caporini
- Bruker Biospin Ltd., Billerica, Massachusetts 01821, United States
| | - Melanie Rosay
- Bruker Biospin Ltd., Billerica, Massachusetts 01821, United States
| | | | | | | | | | - Alex I. Smirnov
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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Coates CS, Milikisiyants S, Chatterjee R, Whittaker MM, Whittaker JW, Lakshmi KV. Two-Dimensional HYSCORE Spectroscopy of Superoxidized Manganese Catalase: A Model for the Oxygen-Evolving Complex of Photosystem II. J Phys Chem B 2015; 119:4905-16. [DOI: 10.1021/acs.jpcb.5b01602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher S. Coates
- Department
of Chemistry and Chemical Biology and The Baruch ’60 Center
for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Sergey Milikisiyants
- Department
of Chemistry and Chemical Biology and The Baruch ’60 Center
for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Ruchira Chatterjee
- Department
of Chemistry and Chemical Biology and The Baruch ’60 Center
for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Mei M. Whittaker
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - James W. Whittaker
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - K. V. Lakshmi
- Department
of Chemistry and Chemical Biology and The Baruch ’60 Center
for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Chatterjee R, Milikisiyants S, Coates CS, Koua FHM, Shen JR, Lakshmi KV. The structure and activation of substrate water molecules in Sr2+-substituted photosystem II. Phys Chem Chem Phys 2014; 16:20834-43. [DOI: 10.1039/c4cp03082f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An EPR spectroscopy study with direct evidence that the Ca2+ ion plays a structural role in maintaining the hydrogen-bond network in photosystem II.
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Affiliation(s)
- Ruchira Chatterjee
- Department of Chemistry and Chemical Biology
- The Baruch ’60 Center for Biochemical Solar Energy Research
- Rensselaer Polytechnic Institute
- Troy, USA
| | - Sergey Milikisiyants
- Department of Chemistry and Chemical Biology
- The Baruch ’60 Center for Biochemical Solar Energy Research
- Rensselaer Polytechnic Institute
- Troy, USA
| | - Christopher S. Coates
- Department of Chemistry and Chemical Biology
- The Baruch ’60 Center for Biochemical Solar Energy Research
- Rensselaer Polytechnic Institute
- Troy, USA
| | - Faisal H. M. Koua
- Photosynthesis Research Center
- Graduate School of Natural Science and Technology and Faculty of Science
- Okayama University
- Okayama 700-8530, Japan
| | - Jian-Ren Shen
- Photosynthesis Research Center
- Graduate School of Natural Science and Technology and Faculty of Science
- Okayama University
- Okayama 700-8530, Japan
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology
- The Baruch ’60 Center for Biochemical Solar Energy Research
- Rensselaer Polytechnic Institute
- Troy, USA
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Chatterjee R, Coates CS, Milikisiyants S, Lee CI, Wagner A, Poluektov OG, Lakshmi KV. High-Frequency Electron Nuclear Double-Resonance Spectroscopy Studies of the Mechanism of Proton-Coupled Electron Transfer at the Tyrosine-D Residue of Photosystem II. Biochemistry 2013; 52:4781-90. [DOI: 10.1021/bi3012093] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ruchira Chatterjee
- Department of Chemistry and
Chemical Biology and The Baruch ’60 Center for Biochemical
Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Christopher S. Coates
- Department of Chemistry and
Chemical Biology and The Baruch ’60 Center for Biochemical
Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Sergey Milikisiyants
- Department of Chemistry and
Chemical Biology and The Baruch ’60 Center for Biochemical
Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Cheng-I Lee
- Department of Life Science, National Chung Cheng University, 168 University Road,
Min-Hsiung, Chia-Yi 621, Taiwan
| | - Arlene Wagner
- Chemical Sciences and Engineering
Division, Argonne National Laboratory,
9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Oleg G. Poluektov
- Chemical Sciences and Engineering
Division, Argonne National Laboratory,
9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - K. V. Lakshmi
- Department of Chemistry and
Chemical Biology and The Baruch ’60 Center for Biochemical
Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Coates CS, Ziegler J, Manz K, Good J, Kang B, Milikisiyants S, Chatterjee R, Hao S, Golbeck JH, Lakshmi KV. The structure and function of quinones in biological solar energy transduction: a cyclic voltammetry, EPR, and hyperfine sub-level correlation (HYSCORE) spectroscopy study of model naphthoquinones. J Phys Chem B 2013; 117:7210-20. [PMID: 23676117 DOI: 10.1021/jp401024p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Quinones function as electron transport cofactors in photosynthesis and cellular respiration. The versatility and functional diversity of quinones is primarily due to the diverse midpoint potentials that are tuned by the substituent effects and interactions with surrounding amino acid residues in the binding site in the protein. In the present study, a library of substituted 1,4-naphthoquinones are analyzed by cyclic voltammetry in both protic and aprotic solvents to determine effects of substituent groups and hydrogen bonds on the midpoint potential. We use continuous-wave electron paramagnetic resonance (EPR) spectroscopy to determine the influence of substituent groups on the electronic properties of the 1,4-naphthoquinone models in an aprotic solvent. The results establish a correlation between the presence of substituent group(s) and the modification of electronic properties and a corresponding shift in the midpoint potential of the naphthoquinone models. Further, we use pulsed EPR spectroscopy to determine the effect of substituent groups on the strength and planarity of the hydrogen bonds of naphthoquinone models in a protic solvent. This study provides support for the tuning of the electronic properties of quinone cofactors by the influence of substituent groups and hydrogen bonding interactions.
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Affiliation(s)
- Christopher S Coates
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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Chatterjee R, Milikisiyants S, Lakshmi KV. Two-dimensional 14N HYSCORE spectroscopy of the coordination geometry of ligands in dimanganese di-μ-oxo mimics of the oxygen evolving complex of photosystem II. Phys Chem Chem Phys 2012; 14:7090-7. [DOI: 10.1039/c2cp40416h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Chatterjee R, Coates CS, Milikisiyants S, Poluektov OG, Lakshmi KV. Structure and Function of Quinones in Biological Solar Energy Transduction: A High-Frequency D-Band EPR Spectroscopy Study of Model Benzoquinones. J Phys Chem B 2011; 116:676-82. [DOI: 10.1021/jp210156a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Christopher S. Coates
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Oleg G. Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Milikisiyants S, Chatterjee R, Lakshmi KV. Two-Dimensional 1H HYSCORE Spectroscopy of Dimanganese Di-μ-oxo Mimics of the Oxygen-Evolving Complex of Photosystem II. J Phys Chem B 2011; 115:12220-9. [DOI: 10.1021/jp205629g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Srinivasan N, Chatterjee R, Milikisiyants S, Golbeck JH, Lakshmi KV. Effect of Hydrogen Bond Strength on the Redox Properties of Phylloquinones: A Two-Dimensional Hyperfine Sublevel Correlation Spectroscopy Study of Photosystem I. Biochemistry 2011; 50:3495-501. [DOI: 10.1021/bi102056q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Nithya Srinivasan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - John H. Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Chatterjee R, Milikisiyants S, Coates CS, Lakshmi KV. High-Resolution Two-Dimensional 1H and 14N Hyperfine Sublevel Correlation Spectroscopy of the Primary Quinone of Photosystem II. Biochemistry 2010; 50:491-501. [DOI: 10.1021/bi101883y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Christopher S. Coates
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Milikisiyants S, Chatterjee R, Weyers A, Meenaghan A, Coates C, Lakshmi KV. Ligand Environment of the S2 State of Photosystem II: A Study of the Hyperfine Interactions of the Tetranuclear Manganese Cluster by 2D 14N HYSCORE Spectroscopy. J Phys Chem B 2010; 114:10905-11. [DOI: 10.1021/jp1061623] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Amanda Weyers
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Ashley Meenaghan
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Christopher Coates
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ′60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
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Weyers AM, Chatterjee R, Milikisiyants S, Lakshmi KV. Structure and Function of Quinones in Biological Solar Energy Transduction: A Differential Pulse Voltammetry, EPR, and Hyperfine Sublevel Correlation (HYSCORE) Spectroscopy Study of Model Benzoquinones. J Phys Chem B 2009; 113:15409-18. [DOI: 10.1021/jp907379d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Amanda M. Weyers
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Ruchira Chatterjee
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Sergey Milikisiyants
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York 12180
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