X-band EPR spectra

Fig. 4. X-band EPR spectra of [Fe3S4]+ clusters in wild type and mutant forms of P. furiosus Fd. All spectra were recorded at 4.2 K microwave power, 1 mW microwave frequency, 9.60 GHz modulation amplitude, 0.63 mT. All samples were in 100 mM Tris-HCl buffer, pH 7.8.

Figure 2.15. X-band EPR spectra recorded after NO adsorption (1 -5 torr) onto ConZSM-5, FenZSM-5 (after [64]), and Cu ZSM-5 (after [41]) zeolites.

Figure 2.20. Transformation of silica supported dinitrosyl complexes of nickel(II) leading to formation of nitrogen dioxide and its final stabilization on the support. The picture shows the molecular structure and the spin density contours calculated with BP/DNP method of the involved species, and evolution of the X-band EPR spectra of the NiN02 Si02 complex due to spillover of the ligand (adopted from [71]).

Figure 9.13 compares X-band EPR spectra of Fe-MCM-41 before (a) and after (b) and (c) carotenoid adsorption. The sample with incorporated Car exhibits a signal with g=2.0028 + 0.0002, characteristic of carotenoid radical cation prior to irradiation (Figure 9.13b). Irradiation of the samples at 365 nm (77 K) increases the Car 1 signal intensity (Figure 9.13c). The X-band experiments (Figure...

There have been conflicting interpretations of the EPR spectra of these selenium-containing complexes. For example, various X-band EPR spectra of Fe(III) diselenocarbamates recorded in chloroform solutions at 12 K tended to be broad and poorly resolved, except for a series of three resonances centred around g=2 [62]. They also appeared to be very similar to the spectra recorded for Mn(III)-doped Co(III) tris(dithiocarbamate) compounds [76] or Cu(II) di(diselenocarbamate) systems [77]. In another study of EPR spectra recorded for powdered Fe(III) thioselenocarbamates and diselenocarbamates at room temperature [69] broad, poorly resolved lines at g 4... 

Figure 25. X-Band EPR spectra of electrochemically generated [Com(L BuMel )(Ph2acac)]2+ (top) and its at the benzylic methylene deuterated analogue (bottom) the hyperfine coupling constants are given in millitesla (mT). [Adapted from (152).]...

Fig. 4.10 X-band epr spectra of Cu(mnt)2 (A) and Cu(mnt)(Et2dsc) (B) at 25 °C. The reaction is monitored at the field strengths indicated by the arrows. Full details for the mixing and accumulation of epr signals are given in Ref. 163. Reproduced with permission from J. Stach, R. Kironse, W. Dietzsch,...

The fully reduced state of CCP is probably of no physiological significance. However, the visible region spectrum of the fully reduced enzyme is very sensitive to the presence or absence of bound Ca + ions. In the absence of Ca + ions the a-band maximum of the reduced enzyme, recorded during the course of the redox titrations described earlier, is at 551 nm with a shoulder at 557 nm. In contrast, in fully reduced Ca +-loaded enzyme the maximum is at 557 nm with a shoulder 551 nm (52). These spectra should be compared with those of the fully reduced Psew-domonas CCP in its inactive and active forms, respectively, which show similar differences (81). Further similarities exist between the X-band EPR spectra of the active CCP from P. aeruginosa in the MV state and that of the Ca +-loaded CCP from P. denitrificans and, moreover, the X-band EPR spectrum of MV P denitrificans CCP that had previously been treated with EDTA (Table I). 

Fig. 9. EPR spectra of heme-hemopexin and heme-N-domain. X-band EPR spectra at 4 K of ferri-mesoheme-hemopexin (a) and ferri-mesoheme-N-domain (b) are shown. The concentration of both heme complexes was 0.15 mM in 50 50 (v/v) 10 mM sodium phosphate/150 mM NaCl (pH 7.2) glycerol. The g-value scale is noted at the top and the -values observed are noted in each spectrum. Although both complexes are low-spin (some adventitious high-spin iron is present), the differences in g-values indicate nonidentical heme environments in the two complexes (.114).

The zero-field splitting constant of the sample ZnS Mn/AA, obtained from X-band EPR spectra, is 9.1 X 10-3 cm-1, which is significantly larger than that from the submicron particles, 2.0 X 10-3 cm-1. This indicates the decrease in the ligand field symmetry by downsizing and addition of AA. 

Figure 4. X-band EPR spectra of BaTi03 Mn powders. (a) Sample processed in air. (b) Sample processed in C02 ...

Fig. 2. The powder X-band EPR spectra of Zn0 99Cu0.oiGreF6 6H20.

Figure 18. X-band EPR spectra of Mn2+ CdS NCs recorded at (a) 300 K and 25-mW power, (b) 4.2 K and 0.25-mW power, and (c) 4.2 K and 250-mW power. The dashed line in (a) was obtained by subtracting signal (b) from signal (a). [Adapted from (63).]...

Figure 19. Panel A is the X-band EPR spectra of colloidal Mn2+ ZnO nanocrystals, (a) Surface-bound Mn2+ ZnO nanocrystals. Samples prepared from 0.02% Mn2+/99.98% Zn2+ reaction solution collected (b) 10 min after base addition, (c) after 2 h of heating at 60°C, and (d) after treating with dodecylamine. Panels B and C are the experimental and simulated 300 K X- and Q-band EPR spectra of colloidal dodecylamine-capped 0.02% Mn2+ ZnO nanocrystals in toluene. Simulations with (XI and Ql) and without (X2 and Q2) a = 2% D-strain are included. [Adapted from (54).]...

Figure 31. (A) The 115 K X-band EPR spectra of (a) TOP-capped 5-nm diameter InAs...

Figure 3.15 Experimental (a) and computer-simulated (b) X-band EPR spectra of a fulvic acid from an arable soil developed from base-rich parent material. Note the octet hyperfine structure patterns associated with the gB and gj features (from Cheshire et at., 1977).

Figure 3.19 X-band EPR spectra of SOD from horseradish as (a) a pure solid, and aqueous solutions at (b) 77 and (c) 298 K (from Palivan ef a/., 1994).

Figure 15.9 Nitroxide dynamics and cw-EPR spectral line-shape. (A) Simulated X-band EPR spectra of nitroxides undergoing isotropic rotation at different rotational correlation time x. (B) The three modes of motion that contribute to nitroxide dynamics. Adopted from Sowa and Qin (2008) with permission.

Figure 3. X-band EPR spectra of Mn- complexes with (Na + K )-ATPase (21). All solutions contained 20mM Tes-TMA, pH 7.5, O.lSmM ATPase, O.ImM MnCI, and the concentrations of the substrates shown.

Figure 4. X-band EPR spectra for Mr2 complexes of (Na -(- K )-ATPase and AMP (21). Conditions were the same as in Figures 2 and 3, with the concentrations of AMP, inorganic phosphate, and sodium chloride shown.

The X-band EPR spectra of vanadium-doped amorphous and PC tetra-gonal Ge02 have been observed even at room temperature (Table 8.8), but there were not recorded for PC hexagonal Ge02 neither at 298 K, nor at 77 K [184]. 

Figure 7. X-band EPR spectra of the one-electron oxidation products of complexes 1-5.

Figure 8. X-band EPR spectra (top), 2nd derivatives (middle), and simulations (bottom) of Tp Cuf NO) (left) and Tpt BuCu(15NO) (right) at 15 K.

The two models for both the peroxide and native intermediates shown in Figure 11 are based on a variety of spectral evidence the most compelling of which is provided by the power-saturation behavior of the native intermediate s EPR spectrum and its EXAFS. Figure 12 compares the X-band EPR spectra of the native intermediate at 77 K (A) with that of the resting oxidized protein (B). The spectra show that in the intermediate, the type 1 copper is fully oxidized, but the type 2 copper is effectively diamagnetic, either... 

Figure 14 X-band EPR spectra of galactose oxidase at 30 K. 1, reductively inactivated 2, native (as isolated) 3, oxidized. (Ref. 54. Reproduced by pemission of American Society for Biochemistry Molecnlar Biology)...

Most X-band EPR spectra of transition metals are recorded at low temperatures (4-lOOK) using high-purity quartz tubes (no paramagnetic impurities) with a sample volume of about 300 pL. The minimum concentration of the sample depends on the broadness of its spectrum. Because EPR spectra are recorded as a first derivative (see subsequent text), the relationship between concentration, signal amplitude and spectral linewidth can be approximated as... 

Figure 5 Proposed catalytic cycle for NO reductase from Pseudomonas aeruginosa (a) and EPR spectra of freeze-quenched samples (b). A The catal)dic nonheme iron Fen, the high-spin heme b, the low-spin heme b, and heme c are indicated from right to left in each state. B Panels A and B show the spectra recorded at 11 and 35 K after atmealing, respectively. Traces a-f show the X-band EPR spectra for the samples quenched at 0.5 ms after mixing the fully reduced NOR with NO buffer and atmealing at 193 K for 120min (trace a), 223 K for 5 min (trace b), 243 K for 5 min (trace c), 263 K for 10 min (trace d), 263 K for 30 min (trace e), and 263 K for 90 min (trace f). The g-values are indicated for the various species. (Reproduced from Kumita, Matsuura, Hino, Takahashi, Hori, Fukumori, Morishima and Shiro by permission of American Society for Biochemistry and Molecular Biology)...

Figure 4 a) X-band EPR spectra of tyrosyl free radical in (i) E. coli, (ii) Mycobacterium tuberculosis, and (iii) mouse ribonucleotide reductase R2 proteins (1 7). All spectra were obtained under nonsaturation conditions at 20 K. b) Spin density distribution of the unpaired electron obtained from Isotope-labeling EPR studies, c) The distances between the phenolic oxygen of tyrosyl radical and the nearest Fe ion deduced from the relaxation properties of the tyrosyl radicals. 

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