The d-Galactose Oxidase of Polyporus circinatus

Avigad, Gad; Amaral, D.; Asensio, Carlos; Horecker, B.L.

doi:10.1016/s0021-9258(18)60220-0

Cited by 465 publications

(83 citation statements)

References 27 publications

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“…The large size of the galactose oxidase molecule inhibits its penetration into red cells (12) and fibroblasts (13), and therefore only surfaceexposed terminal galactosyl and N-acetyl galac-GArlMBERG, HXYRY, AND ANDERSSON Surface Glycoproteins of Lymphoid Cells 647 tosaminyl residues are oxidized to the corresponding C6 aldehydes (5). We have treated intact labeled lymphocytes and thymocytes with pronase and trypsin, to verify the surface distribution of the labeled glycoproteins (not shown).…”

Section: Discussionmentioning

confidence: 99%

Characterization of surface glycoproteins of mouse lymphoid cells.

Gahmberg¹,

Häyry²,

Andersson³

1976

The Journal of Cell Biology

151

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We have labeled exposed surface glycoproteins of mouse lymphoid cells by the galactose oxidase-tritated sodium borohydride technique. The labeled glycoproteins were separated by polyacrylamide slab gel electrophoresis and visualized by autoradiography (fluorography). The major thymocyte surface proteins have molecular weights of 170,000 and 125,000. Thymocytes from TL antigen-positive mouse strains showed an additional band with a molecular weight of 27,000. Highly purified T lymphocytes contain two major surface glycoproteins with molecular weights of 180,000 and 125,000. Purified B lymphocytes have one major surface glycoprotein with a molecular weight of 210,000.When T lymphocytes are stimulated in vitro by concanavalin A or phytohemagglutinin, the major proteins characteristic of T cells are relatively weakly labeled, but new components of lower molecular weights appear on the cell surface. A similar change is seen in B lymphocytes stimulated by Escherichia coli lipopolysaccharide. T lymphoblasts isolated from mixed lymphocyte cultures show a slightly different surface glycoprotein pattern.

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Section: Discussionmentioning

confidence: 99%

Characterization of surface glycoproteins of mouse lymphoid cells.

Gahmberg¹,

Häyry²,

Andersson³

1976

The Journal of Cell Biology

151

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“…The X-ray crystal structure revealed a unique tertiary structure with an active site consisting of a mononuclear copper (Cu) ion and a tyrosyl-cysteine redox cofactor, bearing resemblance to the Cu active site in fungal galactose oxidases (Gox) [18]. Enzymes of this family carry out the two-electron oxidation of primary alcohols to aldehydes with the reduction of dioxygen to hydrogen peroxide [19]. Unlike Gox, the active site Cu and putative substrate binding pocket is buried in GlxA, but can be accessed through channels leading down from three separate surface locations [14].…”

Section: Introductionmentioning

confidence: 99%

The DyP-type peroxidase DtpA is a Tat-substrate required for GlxA maturation and morphogenesis in Streptomyces

et al. 2016

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The filamentous bacterium Streptomyces lividans depends on the radical copper oxidase GlxA for the formation of reproductive aerial structures and, in liquid environments, for the formation of pellets. Incorporation of copper into the active site is essential for the formation of a cross-linked tyrosyl-cysteine cofactor, which is needed for enzymatic activity. In this study, we show a crucial link between GlxA maturation and a group of copper-related proteins including the chaperone Sco and a novel DyP-type peroxidase hereinafter called DtpA. Under copper-limiting conditions, the sco and dtpA deletion mutants are blocked in aerial growth and pellet formation, similarly to a glxA mutant. Western blot analysis showed that GlxA maturation is perturbed in the sco and dtpA mutants, but both maturation and morphology can by rescued by increasing the bioavailability of copper. DtpA acts as a peroxidase in the presence of GlxA and is a substrate for the twin-arginine translocation (Tat) translocation pathway. In agreement, the maturation status of GlxA is also perturbed in tat mutants, which can be compensated for by the addition of copper, thereby partially restoring their morphological defects. Our data support a model wherein a copper-trafficking pathway and Tat-dependent secretion of DtpA link to the GlxA-dependent morphogenesis pathway.

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“…Galactose oxidase (GAOX) 1 (EC 1.1.3.9) is a secretory fungal copper metalloenzyme that generates hydrogen peroxide in the extracellular space by oxidizing simple alcohols and subsequently reducing dioxygen to H 2 O 2 (1)(2)(3)(4). Together with a closely related enzyme, glyoxal oxidase (5,6), galactose oxidase represents a family of radical-copper oxidases defined by the presence of an unusual free radical-coupled copper active site (comprising a free radical associated with a redox-active metal ion) that functions as a two-electron redox unit in substrate oxidation and O 2 reduction (7,8).…”

mentioning

confidence: 99%

Cu(I)-dependent Biogenesis of the Galactose Oxidase Redox Cofactor

Whittaker

2003

Journal of Biological Chemistry

112

174

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Galactose oxidase is a copper metalloenzyme containing a novel protein-derived redox cofactor in its active site, formed by cross-linking two residues, Cys228 and Tyr272. Previous studies have shown that formation of the tyrosyl-cysteine (Tyr-Cys) cofactor is a self-processing step requiring only copper and dioxygen. We have investigated the biogenesis of cofactor-containing galactose oxidase from pregalactose oxidase lacking the Tyr-Cys cross-link but having a fully processed N-terminal sequence, using both Cu(I) and Cu(II). Mature galactose oxidase forms rapidly following exposure of a pregalactose oxidase-Cu(I) complex to dioxygen (t(1/2) = 3.9s at pH7). In contrast, when Cu(II) is used in place of Cu(I) the maturation process requires several hours (t(1/2) = 5.1 h). EDTA prevents reaction of pregalactose oxidase with Cu(II) but does not interfere with the Cu(I)-dependent biogenesis reaction. The yield of cross-link corresponds to the amount of copper added, although a fraction of the pregalactose oxidase protein is unable to undergo this cross-linking reaction. The latter component, which may have an altered conformation, does not interfere with analysis of cofactor biogenesis at low copper loading. The biogenesis product has been quantitatively characterized, and mechanistic studies have been developed for the Cu(I)-dependent reaction, which forms oxidized, mature galactose oxidase and requires two molecules of O2. Transient kinetics studies of the biogenesis reaction have revealed a pH sensitivity that appears to reflect ionization of a protein group (pKa = 7.3) at intermediate pH resulting in a rate acceleration and protonation of an early oxygenated intermediate at lower pH competing with commitment to cofactor formation. These spectroscopic, kinetic, and biochemical results lead to new insights into the biogenesis mechanism.

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The d-Galactose Oxidase of Polyporus circinatus

Cited by 465 publications

References 27 publications

Characterization of surface glycoproteins of mouse lymphoid cells.

Characterization of surface glycoproteins of mouse lymphoid cells.

The DyP-type peroxidase DtpA is a Tat-substrate required for GlxA maturation and morphogenesis in Streptomyces

Cu(I)-dependent Biogenesis of the Galactose Oxidase Redox Cofactor

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