Cellobiose oxidase from <i>Phanerochaete chrysosporium</i> Stopped‐flow spectrophotometric analysis of pH‐dependent reduction

Samejima, Masahiro; Phillips, Robert S.; Eriksson, Karl–Erik L.

doi:10.1016/0014-5793(92)80991-o

Cited by 34 publications

(28 citation statements)

References 12 publications

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“…The reduction of triiodide was also reported [69]. The reduction of these electron acceptors usually takes place at the flavin [70], but as basidiomycete CDHs can shuttle electrons efficiently to the haem at pH values below 5.5 [59] and ascomycete CDHs can shuttle electrons efficiently to the haem even at neutral or increased pH values [37,40,66], it is obvious that oneelectron acceptors can also be reduced at the haem. It is common belief that two-electron acceptors are reduced directly at the flavin domain, but opinions differ pertaining to the reduction of one-electron acceptors.…”

Section: Catalytic Mechanism Of the Oxidative Half-reactionmentioning

confidence: 94%

“…In order to shed light on the mechanism of electron transfer in CDH, the reduction of P. chrysosporium CDH by cellobiose has been investigated by rapid-kinetics studies using stopped-flow spectrophotometry [56,[58][59][60][61][62][63]. The rate of flavin reduction depends on the cellobiose concentration but reaches a rate limit of approx.…”

Section: Interdomain Electron Transfermentioning

confidence: 99%

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Cellobiose Dehydrogenase – A Flavocytochrome from Wood-Degrading, Phytopathogenic and Saprotropic Fungi

Zámocký¹,

Ludwig

Peterbauer

et al. 2006

CPPS

221

230

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Cellobiose dehydrogenase, the only currently known extracellular flavocytochrome, is formed not only by a number of wood-degrading but also by various phytopathogenic fungi. This inducible enzyme participates in early events of lignocellulose degradation, as investigated in several basidiomycete fungi at the transcriptional and translational level. However, its role in the ascomycete fungi is not yet obvious. Comprehensive sequence analysis of CDH-encoding genes and their translational products reveals significant sequence similarities along the entire sequences and also a common domain architecture. All known cellobiose dehydrogenases fall into two related subgroups. Class-I members are represented by sequences from basidiomycetes whereas class-II comprises longer, more complex sequences from ascomycete fungi. Cellobiose dehydrogenase is typically a monomeric protein consisting of two domains joined by a protease-sensitive linker region. Each larger (dehydrogenase) domain is flavin-associated while the smaller (cytochrome) domains are haem-binding. The latter shorter domains are unique sequence motifs for all currently known flavocytochromes. Each cytochrome domain of CDH can bind a single haem b as prosthetic group. The larger dehydrogenase domain belongs to the glucose-methanol-choline (GMC) oxidoreductase superfamily - a widespread flavoprotein evolutionary line. The larger domains can be further divided into a flavin-binding subdomain and a substrate-binding subdomain. In addition, the class-II (but not class-I) proteins can possess a short cellulose-binding module of type 1 at their C-termini. All the cellobiose dehydrogenases oxidise cellobiose, cellodextrins, and lactose to the corresponding lactones using a wide spectrum of different electron acceptors. Their flexible specificity serves as a base for the development of possible biotechnological applications.

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Section: Catalytic Mechanism Of the Oxidative Half-reactionmentioning

confidence: 94%

Section: Interdomain Electron Transfermentioning

confidence: 99%

Cellobiose Dehydrogenase – A Flavocytochrome from Wood-Degrading, Phytopathogenic and Saprotropic Fungi

Zámocký¹,

Ludwig

Peterbauer

et al. 2006

CPPS

221

230

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“…It has been reported that both cytochrome c and DCPIP were reduced by CDH at pH 4.2, whereas only DCPIP was reduced effectively at pH 5.9. This phenomenon was explained by stopped-flow kinetic study that both flavin and heme were reduced at a high rate at pH 4.2, whereas only flavin reduction proceeded quickly at pH 5.9 (18). From these observations, the reduction of cytochrome c is dependent on heme, and an electron is transferred from cellobiose to this electron acceptor via both FAD and heme, whereas the reduction of DCPIP is catalyzed only by flavin.…”

mentioning

confidence: 95%

Cellobiose Dehydrogenase from the Fungi Phanerochaete chrysosporium and Humicola insolens

Igarashi¹,

Verhagen²,

Samejima³

et al. 1999

Journal of Biological Chemistry

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Cellobiose dehydrogenases (CDH) were purified from cellulose-grown cultures of the fungi Phanerochaete chrysosporium and Humicola insolens. The pH optimum of the cellobiose-cytochrome c oxidoreductase activity of P. chrysosporium CDH was acidic, whereas that of H. insolens CDH was neutral. The absorption spectra of the two CDHs showed them to be typical hemoproteins, but there was a small difference in the visible region. Limited proteolysis between the heme and flavin domains was performed to investigate the cofactors. There was no difference in absorption spectrum between the heme domains of P. chrysosporium and H. insolens CDHs. The midpoint potentials of heme at pH 7.0 were almost identical, and no difference in pH dependence was observed over the range of pH 3-9. The pH dependence of cellobiose oxidation by the flavin domains was similar to that of the native CDHs, indicating that the difference in the pH dependence of the catalytic activity between the two CDHs is because of the flavin domains. The absorption spectrum of the flavin domain from H. insolens CDH has absorbance maxima at 343 and 426 and a broad absorption peak at 660 nm, whereas that of P. chrysosporium CDH showed a normal flavoprotein spectrum. Flavin cofactors were extracted from the flavin domains and analyzed by high-performance liquid chromatography. The flavin cofactor from H. insolens was found to be a mixture of 60% 6-hydroxy-FAD and 40% FAD, whereas that from P. chrysosporium CDH was normal FAD. After reconstitution of the deflavo-proteins it was found that flavin domains containing 6-hydroxy-FAD were clearly active but their cellobiose oxidation rates were lower than those of flavin domains containing normal FAD. Reconstitution of flavin cofactor had no effect on the optimum pH. From these results, it is concluded that the pH dependence is not because of the flavin cofactor but is because of the protein molecule.

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“…Jones and Wilson (27) observed that the rate constant for heme iron reduction in CDH increases with enzyme concentration and interpreted this as due to the intermolecular reduction of the heme center by flavin groups; whereas, in the case of flavocytochrome b 2 , electron transfer from flavin to heme is intramolecular (79). Samejima et al (28) studied the effect of pH on the reduction of cytochrome c and dichlorophenol-indophenol by CDH.…”

Section: Kinetic Studiesmentioning

confidence: 99%

Cellobiose Dehydrogenase

Renganathan

Bao

1994

ACS Symposium Series

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Cellobiose oxidase from Phanerochaete chrysosporium Stopped‐flow spectrophotometric analysis of pH‐dependent reduction

Cited by 34 publications

References 12 publications

Cellobiose Dehydrogenase – A Flavocytochrome from Wood-Degrading, Phytopathogenic and Saprotropic Fungi

Cellobiose Dehydrogenase – A Flavocytochrome from Wood-Degrading, Phytopathogenic and Saprotropic Fungi

Cellobiose Dehydrogenase from the Fungi Phanerochaete chrysosporium and Humicola insolens

Cellobiose Dehydrogenase

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