ESR of Copper in Biological Systems

Boas, John F.; Pilbrow, John R.; Smith, Thomas D.

doi:10.1007/978-1-4615-6534-5_7

Cited by 12 publications

(9 citation statements)

References 311 publications

(140 reference statements)

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“…Distinction between protein-bound and free Cu ions is made by differences in the values of the spectroscopic constants g and A. The data in Table 1 show that the homogenates and ES of N. americanus have values for g and A similar to those described previously for Cu/Zn SOD [22] and distinct from aqueous Cu [23]. Spectral simulation for comparison with experimental results reveals the presence of two different protein-bound Cu ions in both ES and homogenate of N. americanus.…”

Section: Metal Content Of Helminth Es Productsupporting

confidence: 63%

Cu/Zn superoxide dismutase in excretory–secretory products of the human hookworm Necator americanus

Taiwo

Brophy

Pritchard

et al. 1999

European Journal of Biochemistry

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EPR spectrometry was used to investigate the effect of excretory/secretory product from Necator americanus on superoxide radical anions generated by xanthine/xanthine oxidase as a measure of excretory/secretory product superoxide dismutase activity. Using 1,1 H ,5,5 H -dimethylpyrollidine-N-oxide (DMPO) as a superoxide spintrapping agent a 12-line EPR spectrum characteristic of the DMPO-OOH adduct was observed to decrease in the presence of excretory/secretory product. Superoxide dismutase activity was proportional to excretory/secretory protein concentration, was inhibited with cyanide treatment and was progressively destroyed with increasing time of heat denaturation of excretory/secretory product. Using a purpose-built chamber the superoxide dismutase activity of excretory/secretory product from live worms in culture was shown to accumulate with time to a maximum at 4 h. The electron paramagnetic resonance spectrum obtained for the frozen excretory/secretory product of N. americanus recorded at 77 K is typical of Cu(II) in a protein matrix. The results are consistent with the presence of an active Cu/Zn superoxide dismutase in excretory/secretory product from N. americanus and demonstrate a method for the unequivocal determination of the fate of superoxide anions in the presence of live worms.

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Section: Metal Content Of Helminth Es Productsupporting

confidence: 63%

Cu/Zn superoxide dismutase in excretory–secretory products of the human hookworm Necator americanus

Taiwo

Brophy

Pritchard

et al. 1999

European Journal of Biochemistry

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“…1 for two a 2 = 0.9 and a 2 = 0.8 values and g \ = 2.099. Collections of experimental data for various complexes confirmed the linear dependence A || vs. g || and show that the dashed lines lies in the parameter range where characteristic for Cu complexes having four oxygen atoms in the main coordination plane of the squareplanar configuration [2][3][4][5][6][7][8][9][10]. A plot of experimental A || vs. g || is called the Peisach-Blumberg correlation diagram since they collected experimental data for many various Cu 2+ complexes [3] allowing an analysis a correlation between EPR parameters.…”

Section: Introductionmentioning

confidence: 89%

EPR and ESE of CuS4 complex in Cu(dmit)2: g-Factor and hyperfine splitting correlation in tetrahedral Cu–sulfur complexes

Hoffmann

Goslar

Lijewski

et al. 2013

Journal of Magnetic Resonance

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“…However, with B 1 || B 0 , the half-field features at 160 mT were 70 times more intense relative to the features at 298, 336, and 362 mT and, thus, confirm their assignment to an S = 1 system. [41][42][43][44] The temperature dependencies of the signals were studied, and the data for the high pH B 1 ⊥ B 0 signal in the g ~2 region at 298 mT and for the B 1 || B 0 signal at 160 mT are presented in Figure 5. Figure 5A shows a region of the spectrum of Figure 3C with the low-field region multiplied by nine and shown above the main trace.…”

Section: Epr Studies On Cu(ii)-substituted Aapmentioning

confidence: 99%

Structurally Distinct Active Sites in the Copper(II)-Substituted Aminopeptidases from Aeromonas proteolytica and Escherichia coli

et al. 2002

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The aminopeptidase from Aeromonas proteolytica (AAP) was titrated with copper, which bound sequentially at two distinct sites. Both the mono-and disubstituted forms of AAP exhibited catalytic hyperactivity relative to the native dizinc enzyme. Monosubstituted AAP exhibited an axial Cu(II) EPR spectrum with slight pH dependence: at pH 6.0 g || =2.249, g ⊥ = 2.055, and A || ( 63/65 Cu) = 1.77 × 10 −2 cm −1 , whereas at pH 9.65 g || = 2.245, g ⊥ = 2.056, and A || ( 63/65 Cu) = 1.77 × 10 −2 cm −1 . These data indicate oxygen and nitrogen ligation of Cu. AAP further substituted with copper exhibited a complex signal with features around g ~2 and 4. The features at g ~4 were relatively weak in the B 0 ⊥ B 1 (perpendicular) mode EPR spectrum but were intense in the B 0 || B 1 (parallel) mode spectrum. The g ~2 region of the perpendicular mode spectrum exhibited two components, one corresponding to mononuclear Cu(II) with g || = 2.218, g ⊥ = 2.023, and A || ( 63/65 Cu) = 1.55 × 10 −2 cm −1 and likely due to adventitious binding of Cu(II) to a site distant from the active site. Excellent simulations were obtained for the second component of the spectrum assuming that two Cu(II) ions experience dipolar coupling corresponding to an inter-copper distance of 5 Å with the two Cu(II) g z directions parallel to each other and at an angle of ~17° to the inter-copper vector (ℋ= βB·g CuA ·S CuA + βB·g CuB ·S CuB + [S·A·I] CuA + [S·A·I] CuB + [S CuA ·J·S CuB ]; g ||(CuA,CuB) = 2.218, g ⊥(CuA,CuB) = 2.060; A ||(CuA,CuB) ( 63/65 Cu) = 1.59 × 10 −2 cm −1 , J isotropic = 50 cm −1 , r Cu-Cu = 4.93 Å, and χ=17°). The exchange coupling between the two copper ions was found to be ferromagnetic as the signals exhibited Curie law temperature dependence. The Cu-Cu distance of ~5 Å indicated by EPR was significantly higher than the inter-zinc distance of 3.5 Å in the native enzyme, and the dicopper species therefore represents a novel dinuclear site capable of catalysis of hydrolysis. In contrast to AAP, the related methionyl aminopeptidase from Escherichia coli (EcMetAP) was found to bind only one Cu(II) ion despite possessing a dinuclear binding site motif. A further difference was the marked pH dependence of the signal in EcMetAP, suggestive of a change in ligation. The structural motifs of these two Cu(II)-substituted aminopeptidases provide important insight into the observed catalytic activity.

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ESR of Copper in Biological Systems

Cited by 12 publications

References 311 publications

Cu/Zn superoxide dismutase in excretory–secretory products of the human hookworm Necator americanus

Cu/Zn superoxide dismutase in excretory–secretory products of the human hookworm Necator americanus

EPR and ESE of CuS4 complex in Cu(dmit)2: g-Factor and hyperfine splitting correlation in tetrahedral Cu–sulfur complexes

Structurally Distinct Active Sites in the Copper(II)-Substituted Aminopeptidases from Aeromonas proteolytica and Escherichia coli

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