Magnetic properties of Cancer magister hemocyanin

Th, Moss; Dc, Gould; Ehrenberg, Anders; Js, Loehr; Hs, Mason

doi:10.1021/bi00737a012

Cited by 49 publications

(13 citation statements)

References 32 publications

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“…Previous magnetic susceptibility measurements showed oxyhemocyanin to be diamagnetic over the temperature range 35-250 K (13,14). Over this same range, the susceptibility of Rhus laccase showed, in addition to the Curie law paramagnetism of copper types 1 and 2, non-Curie paramagnetism at temperatures above 80 K that was consistent with an antiferromagnetically coupled Cu(II) pair with J = 170 ± 30 cm1 (13).…”

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confidence: 74%

“…The four copper atoms in laccase are distributed in types 1 (paramagnetic), 2 (paramagnetic), and 3 (binuclear; EPR nondetectable) sites. The type 3 coppers apparently function as a two-electron acceptor and are thought to be the site of interaction with dioxygen (3).Previous magnetic susceptibility measurements showed oxyhemocyanin to be diamagnetic over the temperature range 35-250 K (13,14). Over this same range, the susceptibility of Rhus laccase showed, in addition to the Curie law paramagnetism of copper types 1 and 2, non-Curie paramagnetism at temperatures above 80 K that was consistent with an antiferromagnetically coupled Cu(II) pair with J = 170 ± 30 cm1 (13).…”

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confidence: 99%

See 1 more Smart Citation

Magnetic susceptibility studies of laccase and oxyhemocyanin.

Dooley¹,

Scott²,

Ellinghaus³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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(1,2), and the oxidases laccase, ascorbate oxidase, and ceruloplasmin (3). Additionally cytochrome c oxidase has been proposed to contain a coupled heme ironcopper pair as the site of dioxygen binding and reduction (4). In no case has any electron paramagnetic resonance (EPR) signal attributable to a binuclear site been observed in the native protein (5). Although other structural possibilities are consistent with this observation, it is generally thought that the metal ions involved are strongly antiferromagnetically coupled, resulting in a diamagnetic or even spin ground state (5, 6). The temperature dependence of the magnetic susceptibility of such systems is distinctive and may be used to distinguish antiferromagnetic coupling from a truly diamagnetic structure-e.g., a Cu(I) dimer. For two antiferromagnetically coupled S = 1/2 Cu(II) ions, the susceptibility will be a maximum at a temperature that is simply related to the energy difference, J, between the diamagnetic ground state and the paramagnetic excited state (7). Antiferromagnetic coupling between two copper ions has been observed in a wide variety of dimeric Cu(II) complexes (8) and in the four-copper derivative of bovine superoxide dismutase (9). We have focused our efforts on oxyhemocyanin and laccase. It is generally accepted that the dioxygen binding site in oxyhemocyanin is a binuclear copper(II) peroxo complex, the evidence coming mainly from resonance Raman (10) and other spectroscopic (11,12) experiments. The four copper atoms in laccase are distributed in types 1 (paramagnetic), 2 (paramagnetic), and 3 (binuclear; EPR nondetectable) sites. The type 3 coppers apparently function as a two-electron acceptor and are thought to be the site of interaction with dioxygen (3).Previous magnetic susceptibility measurements showed oxyhemocyanin to be diamagnetic over the temperature range 35-250 K (13,14). Over this same range, the susceptibility of Rhus laccase showed, in addition to the Curie law paramagnetism of copper types 1 and 2, non-Curie paramagnetism at temperatures above 80 K that was consistent with an antiferromagnetically coupled Cu(II) pair with J = 170 ± 30 cm1 (13).Owing to the fact that the fit of theory to the observed deviation from Curie law in laccase was not entirely satisfactory (due in part to the low precision of the measurements) and realizing the importance of these observations to understanding the copper-site electronic structure of hemocyanin and laccase, we have remeasured the susceptibilities over a wider temperature range by using susceptometers recently developed at SHE Corporation, San Diego, CA. Although oxyhemocyanin was again observed to be essentially diamagnetic over the entire temperature range, laccase, in contrast to our previous results, displayed only the Curie law behavior of copper types 1 and 2 over the temperature range examined. MATERIALS AND METHODSRhus vernidfera laccase was purified by the method of Reinhammar (15) from the acetone powder (Saito & Co., Ltd., Japan) to a A2o/A614 value <15. A sample w...

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confidence: 74%

mentioning

confidence: 99%

Magnetic susceptibility studies of laccase and oxyhemocyanin.

Dooley¹,

Scott²,

Ellinghaus³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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“…[We thank Nikolaos S. Thomaidis (University of Athens, Athens, Greece) for these measurements.] Note, however, that most of the Cu will be bound to the insect blood pigment, hemocyanin, in a diamagnetic state (76) and will not contribute to the signal. As a simple check for changes in the redox state of iron, we looked for a signal at g ∼ 4.0 (typical of high-spin iron in complexes) (77) and found none.…”

Section: Discussionmentioning

confidence: 99%

Electron spin changes during general anesthesia in Drosophila

Turin

Skoulakis

Horsfield

2014

Proc. Natl. Acad. Sci. U.S.A.

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We show that the general anesthetics xenon, sulfur hexafluoride, nitrous oxide, and chloroform cause rapid increases of different magnitude and time course in the electron spin content of Drosophila. With the exception of CHCl 3 , these changes are reversible. Anesthetic-resistant mutant strains of Drosophila exhibit a different pattern of spin responses to anesthetic. In two such mutants, the spin response to CHCl 3 is absent. We propose that these spin changes are caused by perturbation of the electronic structure of proteins by general anesthetics. Using density functional theory, we show that general anesthetics perturb and extend the highest occupied molecular orbital of a nine-residue α-helix. The calculated perturbations are qualitatively in accord with the Meyer-Overton relationship and some of its exceptions. We conclude that there may be a connection between spin, electron currents in cells, and the functioning of the nervous system.

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“…The remainder, which is the component thought to be involved in oxygen binding, probably contains pairs of antiferromagnetically coupled copper II ions separated by oxygen molecules. Susceptibility measurements on the oxyhemocyanin of the keyhole limpet M egathara crenulata indicates a value of J> -625 cm -1 (Solomon et aI., 1976a), which is rather larger than previously thought (Moss et al, 1973). Resonance Raman spectral studies have shown that the oxygen is bound in oxyhemocyanin in a peroxy form (Loehr et al, 1974).…”

Section: Arthropod and Molluscan Bloodstreams-hemocyaninmentioning

confidence: 94%