Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.2 (laccase)
 4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Binuclear cupric ion clusters have been established in: human ceruloplasmin, hemocyanin, and mushroom tyrosinase. Substantial evidence makes it very probable that fungal laccase and zucchini ascorbate oxidase contain this cluster. Some evidence makes it possible that copper clusters function in the catalytic cycles of cytochrome oxidase (mammalian) and dopamine-beta-hydroxylase. These studies throw light on the criteria which must be employed to establish the existence of functional binuclear copper clusters in enzymes: (1) Stoichiometric Criteria: binding of O2 and CO with Cu/ligand = 2; redox titrations with n = 2; (2) Physical and Chemical Criteria: magnetic evidence of diminished paramagnetism of cupric centers, EPR evidence of broadened or absent absorptions, EPR evidence of magnetic dipolar interactions among cupric ions; absorption bands characteristic of Cu(II)-Cu(II) complexes; laser resonance raman scattering characteristic of peroxidic dioxygen in the oxyforms.
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PMID:Binuclear copper clusters as active sites for oxidases. 18 78

The method of continuous saturation has been used to measure the electron spin relaxation parameter T1T2 at temperatures between 10 and 50 K for a variety of S = 1/2 species including: CuA and cytochrome a of cytochrome c oxidase, the type 1 copper in several blue copper proteins, the type 2 copper in laccase, inorganic Cu(II) complexes, sulfur radicals, and low spin heme proteins. The temperature dependence and the magnitude of T1T2 for all of the species examined are accounted for by assuming that the Van Vleck Raman process dominates the electron spin-lattice relaxation. Over the entire temperature range examined, the relaxation of the type 1 coppers in six to seven times faster than that of type 2 copper, inorganic copper, and sulfur radicals, in spite of the similar g-anisotropies of these species. This result may indicate that the coupling of the phonon bath to the spin center is more effective in type 1 coppers than in the other complexes studied. The relaxation of CuA of cytochrome oxidase exhibits an unusual temperature dependence relative to the other copper complexes studied, suggesting that the protein environment of this center is different from that of the other copper centers studied and/or that CuA is influenced by a magnetic dipolar interaction with another, faster-relaxing paramagnetic site in the enzyme. A comparison of the saturation characteristics of the CuA EPR signal in native and partially reduced CO complexes of the enzyme also suggests the existence of such an interaction. The implications of these results with respect to the disposition of the metal centers in cytochrome oxidase are discussed.
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PMID:Electron spin relaxation of CuA and cytochrome a in cytochrome c oxidase. Comparison to heme, copper, and sulfur radical complexes. 608 26

Cryptococcus neoformans is subject to oxidative attack by host immune cells; consequently, oxidant-resistant mechanisms may be important in pathogenesis. Mutations at the OXY2 locus confer decreased laccase and increased sensitivity to hyperbaric oxygen in the background of the oxyl mutation, but, alone, do not confer sensitivity to oxidants. Because metal deficiency can potentiate or ameliorate sensitivity to oxidants, and because the melanin-synthesizing laccase contains copper, we investigated copper acquisition in an oxy2 mutant. We found that its external Cu/Fe reductase activity was lower than that of wild type, and although copper deprivation induced the reductase in the wild type, it did not do so in oxy2. Oxy2 is sensitive to copper chelation but resistant to high copper, suggesting that copper transport is decreased. The strain expresses large amounts of alternate oxidase in response to Cu-chelation, perhaps in response to defective, Cu-deprived cytochrome oxidase, and is resistant to the oxidant, plumbagin, under this condition, perhaps due to the high alternate oxidase. These phenotypes are similar to those of the mac1- mutant of Saccharomyces cerevisiae and the melanin-deficient grisea mutant of Podospora anserina, in which homologous transcriptional activators for the reductase and copper transporter genes are mutated. They constitute physiologic evidence that oxy2 is mutated in a homologous copper-related transcriptional activator of C. neoformans.
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PMID:Oxy2 as a transcriptional activator gene for copper uptake in Cryptococcus neoformans. 1547 57

Phialocephala fortinii s.1. and Acephala applanata are the dominant dark septate endophytes (DSE) in roots of many trees and shrubs. Population genetic analysis led to the discovery of morphologically indistinguishable but reproductively isolated cryptic species (CSP) within Phialocephala fortinii s.1. In the present study we show that sequence data of two coding (beta-tubulin and translation elongation factor [EF-lalpha]) and three noncoding DNA loci confirm subdivision of P. fortinii s.1. and allow to differentiate seven CSP of P. fortinii. In addition we show that strains collected throughout Europe can be classified correctly based on these sequence markers. Statistically significant differences in growth response on different media were observed among CSP of P. fortinii and A. applanata. Growth inhibition on MEA amended with 100 mgl(-1) cycloheximide had the strongest differential effect of all physiological traits examined. In contrast exoenzyme production (laccase, proteinase, pectinase, phenol-oxidase, amylase, cytochrome oxidase and tyrosinase) rarely helped to differentiate CSP of P. fortinii. However A. applanata was a strong producer of amylases, laccases and proteinases. Based on these data we propose to assign species rank to six CSP of P. fortinii: P. turiciensis, P. letzii, P. europaea, P. helvetica, P. uotolensis, P. subalpina spp. nov. and P. fortinii s.s.
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PMID:Assignment of species rank to six reproductively isolated cryptic species of the Phialocephala fortinii s.1.-Acephala applanata species complex. 1848 52