A resonance enhancement of the phase relaxation in the electron spin echo of nitroxide covalently attached to cytochrome c

Hilczer, W.; Goslar, J.; Gramza, M.; Hoffmann, S. K.; Blicharski, Wojciech; Osyczka, Artur; B, Turyna; Froncisz, Wojciech

doi:10.1016/s0009-2614(95)01238-9

Cited by 8 publications

(3 citation statements)

References 26 publications

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“…Thus, the relaxation enhancement is due to the dipolar interaction with the framework Ti 3+ ions and not due to the hyperfine interaction as a result of the rotation of the carotenoid methyl groups. A similar dramatic increase in 1/ T M has been observed for spin-labeled oxidized cytochrome c and for spin-labeled metmyoglobin. , The relaxation rates of the 2 radical in siliceous MCM-41 (1/ T M0 ) and in TiMCM-41 (1/ T M ) are listed in the Supporting Information.…”

Section: Resultssupporting

confidence: 71%

Measuring Ti(III)−Carotenoid Radical Interspin Distances in TiMCM-41 by Pulsed EPR Relaxation Enhancement Method

Konovalova

Polyakov

et al. 2009

J. Phys. Chem. B

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Interspin distances between the Ti(3+) ions and the carotenoid radicals produced inside TiMCM-41 pores by photoinduced electron transfer from 7'-apo-7'-(4-carboxyphenyl)-beta-carotene (coordinated to Ti(3+)), canthaxanthin (formed as a random distribution of isomers), and beta-ionone (model for a short-chain polyene) to Ti(3+) framework sites were determined using the pulsed EPR relaxation enhancement method. To estimate the electron transfer distances, the temperature dependence of relaxation rates was analyzed in both siliceous and metal-substituted siliceous materials. The phase memory times, T(M), of the carotenoid radicals were determined from the best fits of two-pulse ESEEM curves. The spin-lattice relaxation times, T(1), of the Ti(3+) ion were obtained from the inversion recovery experiment with echo detection on a logarithmic time scale in the temperature range of 10-150 K. The relaxation enhancement for the carotenoid radicals in TiMCM-41 as compared to that in MCM-41 is consistent with an interaction between the radical and the fast relaxing Ti(3+) ion. For canthaxanthin and beta-ionone, a dramatic effect on the carotenoid relaxation rate, 1/T(M), occurs at 125 and 40 K, respectively, whereas for carboxy-beta-carotene 1/T(M) increases monotonically with increasing temperature. The interspin distances for canthaxanthin and beta-ionone were estimated from the 1/T(M) - 1/T(M0) difference, which corresponds to the Ti(3+) contribution at the temperature where the maximum enhancement in the relaxation rate occurs. Determination of the interspin distances is based on calculations of the dipolar interaction, taking into consideration the unpaired spin density distribution along the 20-carbon polyene chain, which makes it possible to obtain a fit over a wider temperature interval. A distribution of the interspin distances between the carotenoid radical and the Ti(3+) ion was obtained with the best fit at approximately 10 A for canthaxanthin and beta-ionone and approximately 9 A for 7'-apo-7'-(4-carboxyphenyl)-beta-carotene with an estimated error of +/-3 A. The interspin distances do not depend on 1/T(M) - 1/T(M0) for carboxy-beta-carotene which shows no prominent peak in the relaxation rate over the temperature range measured.

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Section: Resultssupporting

confidence: 71%

Measuring Ti(III)−Carotenoid Radical Interspin Distances in TiMCM-41 by Pulsed EPR Relaxation Enhancement Method

Konovalova

Polyakov

et al. 2009

J. Phys. Chem. B

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“…2(B) shows a distinctly different temperature dependence of T 2 from Samples A and C. At high and low temperatures, T 2 approaches 0.7 ms, close to that in Samples A and C. However, T 2 drops down at intermediate temperatures reaching a minimum of 0.45 ms (a 35% reduction) at around 15 K. This type of T 2 temperature dependence has been observed in situations where thermally activated electric or magnetic field noise dominates spin relaxation. [31][32][33] As temperature decreases the characteristic time of this noise (τ c ) increases, making a transition from a motional narrowing regime (τ c ≪ T 2 ) at high temperatures to a slow spectral diffusion regime (τ c ≫ T 2 ) at low temperatures. The effect of noise is minimal in these two extreme regimes (therefore long T 2 ), however the effect on T 2 can become significant in the intermediate regime when…”

Section: A Nvmentioning

confidence: 99%

Spin coherence and 14 N ESEEM effects of nitrogen-vacancy centers in diamond with X-band pulsed ESR

Rose

Weis

Tyryshkin

et al. 2017

Diamond and Related Materials

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Pulsed ESR experiments are reported for ensembles of negatively-charged nitrogen-vacancy centers (NV − ) in diamonds at X-band magnetic fields (280-400 mT) and low temperatures (2-70 K). The NV − centers in synthetic type IIb diamonds (nitrogen impurity concentration < 1 ppm) are prepared with bulk concentrations of 2 · 10 13 cm −3 to 4 · 10 14 cm −3 by high-energy electron irradiation and subsequent annealing. We find that a proper post-radiation anneal (1000• C for 60 mins) is critically important to repair the radiation damage and to recover long electron spin coherence times for NV − s. After the annealing, spin coherence times of T2 = 0.74 ms at 5 K are achieved, being only limited by 13 C nuclear spectral diffusion in natural abundance diamonds. At X-band magnetic fields, strong electron spin echo envelope modulation (ESEEM) is observed originating from the central 14 N nucleus. The ESEEM spectral analysis allows for accurate determination of the 14 N nuclear hypefine and quadrupole tensors. In addition, the ESEEM effects from two proximal 13 C sites (second-nearest neighbor and fourth-nearest neighbor) are resolved and the respective 13 C hyperfine coupling constants are extracted.

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“…Therefore, the cleaved Cyt c is unable to quench the FL of GQDs. 37,43 Furthermore, the FL maximum of the GQDs-Cyt c complex is scarcely inuenced by the addition of trypsin (curve 3, Fig. 2b), demonstrating the existence of GQDs aggregation states induced by Cyt c fragments (Fig.…”

mentioning

confidence: 98%

Self-assembled graphene quantum dots induced by cytochrome c: a novel biosensor for trypsin with remarkable fluorescence enhancement

Zhu

et al. 2013

Nanoscale

138

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A resonance enhancement of the phase relaxation in the electron spin echo of nitroxide covalently attached to cytochrome c

Cited by 8 publications

References 26 publications

Measuring Ti(III)−Carotenoid Radical Interspin Distances in TiMCM-41 by Pulsed EPR Relaxation Enhancement Method

Measuring Ti(III)−Carotenoid Radical Interspin Distances in TiMCM-41 by Pulsed EPR Relaxation Enhancement Method

Spin coherence and 14 N ESEEM effects of nitrogen-vacancy centers in diamond with X-band pulsed ESR

Self-assembled graphene quantum dots induced by cytochrome c: a novel biosensor for trypsin with remarkable fluorescence enhancement

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