Infrared and visible circular dichroism and magnetic circular dichroism studies on cobalt(II)-substituted blue copper proteins

Solomon, Edward I.; Rawlings, J.; McMillin, David R.; Stephens, P. J.; Gray, Harry B.

doi:10.1021/ja00441a028

Cited by 51 publications

(38 citation statements)

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“…The enzyme has four copper atoms per molecule capable of accepting four electrons consisting of one type 1 copper II, one type 2 copper II, and the type 3 copper II pair (Nakamura, 1958;Makino and Ogura, 1971;Reinhammar and Vanngard, 1971). Magnetic susceptibility measurements on Rhus laccase have been carried out by Solomon et al (1976b), who determined the antiferromagnetic coupling of the type 3 copper II pairs to be 170 ± 30 em -1. The electron transfer reactions of copper proteins including those of the laccases have been summarized by Howerda et al (1976), while Fee (1975) has outlined, in detail, aspects of the mechanism of the oxidation process catalyzed by laccases.…”

Section: Laccasesmentioning

confidence: 99%

ESR of Copper in Biological Systems

Boas

Pilbrow

Smith

1978

Biological Magnetic Resonance

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Section: Laccasesmentioning

confidence: 99%

ESR of Copper in Biological Systems

Boas

Pilbrow

Smith

1978

Biological Magnetic Resonance

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“…11-14 and unpublished data) and cobalt-substituted (11,(15)(16)(17) blue proteins have indicated a near tetrahedral geometry for type 1 copper; for plastocyanin (18) and azurin (19), preliminary x-ray crystallographic results have shown that the copper ligands are two histidines, a cysteine anion, and a methionine. In contrast, much less is known about the exact coordination environment of type 2 copper.…”

mentioning

confidence: 94%

Coordination environment and fluoride binding of type 2 copper in the blue copper oxidase ceruloplasmin.

Dawson¹,

Dooley²,

Gray³

1978

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

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“…Here we show details of the direct electrochemistry of stellacyanin. Few kinetic studies have been performed on stellacyanin [41-451 compared to a variety of optical and magnetic studies [8,[46][47][48][49].…”

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confidence: 99%

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

Ikeda

Sakurai

1994

European Journal of Biochemistry

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Direct (unmediated) electrochemistry of Rhus verniciferu stellacyanin at a glassy carbon electrode has been briefly investigated in phosphate buffer. The voltammetry was practically independent of the buffer concentration, suggesting that the interaction between stellacyanin and the glassy carbon electrode is mainly realized through the hydrophobic interaction. The quasi-reversible process was found to be diffusion controlled at a sweep rate < 80 mVs-I. From stellacyanin concentration dependence, a transformation from linear diffusion to radial diffusion was observed. Twostep voltammetry was affected by translocations of the active site (rotation of the protein molecule on the electrode surface and diffusion). Activation energies for reduction and oxidation processes were determined to be 24kJmol-' and 54k.Tmol-l, respectively, by the stationary method, and 15 k.Tmol-' and 66 Hmol-I, respectively, by cyclic voltammetry. The considerable difference in the activation energies is supposedly due to the reduction and oxidation which are performed utilizing different electron-transfer pathways or because only one electron-transfer pathway (probably through His92) is significantly changed during the reorganization between the oxidized and reduced forms. The fact that the diffusion constant estimated from one-step voltammetry (Dox= 4.2 X10-9 cm2 s-I for 484 pM stellacyanin) is much smaller than that determined from cyclic voltammetry (7.5X10-7 cm2 s-I) derives from the fact that motions of the stellacyanin molecule (rotation leading to translocation of the active site and diffusion) are not fast enough to allow data from potential step voltammetry to be treated as the reversible process, but are fast enough to allow data from cyclic voltammetry to be treated as a diffusion-controlled process.The electron-transfer reaction has received special attention for more than fifty years, since it is involved in important biological processes such as photosynthesis and respiration [l-41. Many of the studies have focused on revealing how the electron-transfer chains are constituted by the relevant proteins, how the redox couple recognize each other, and how the intermolecular and intramolecular electron transfers take place.The rate of the biological electron-transfer processes depends on an interplay of several factors such as the distance between the donor and acceptor, their orientation with respect to each other, the nature of the intervening medium and the groups involved in the transfer pathway, the thermodynamic driving force, and atomic motions coupled with electron transfer [ 5 ] .Together with cytochromes and iron-sulfur proteins, blue copper proteins also play a role in biological electron transfers [6, 71. This type of metalloprotein contains only oneCorrespondence to

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Infrared and visible circular dichroism and magnetic circular dichroism studies on cobalt(II)-substituted blue copper proteins

Cited by 51 publications

References 8 publications

ESR of Copper in Biological Systems

ESR of Copper in Biological Systems

Coordination environment and fluoride binding of type 2 copper in the blue copper oxidase ceruloplasmin.

Electron transfer reaction of stellacyanin at a bare glassy carbon electrode

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