Reactions of reduced cellobiose oxidase with oxygen. Is cellobiose oxidase primarily an oxidase?

Wilson, Michael T.; Hogg, Neil; Jones, Gareth D.

doi:10.1042/bj2700265

Cited by 36 publications

(21 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several recent reports [5,10,11] suggest that atmospheric oxygen is a poor electron acceptor for CBO, contrary to its nomenclature. The in vivo electron aceeptor for CBO still seems to be unknown.…”

Section: Discussionmentioning

confidence: 92%

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

1992

View full text Add to dashboard Cite

Cellobiose oxidase (CBO) from Phaneroehaete cho,sospor [um can utili~ dichlorph¢nol-indoplmnol (CMnd) and cytochrorne c as effective electron aeceptors for the oxidation of c¢llobiose. However, the pH dependencies of activity for these electron aew.eptors me significantly different. Both compounds act as effective electron acceptors at pH 4..2, whereas only dichlorophenol-indophenol is active at pH ri.9. To explain this discrcpanc),, the pH dependencies of the reduction rates of FAD and home, respectively, in CBO b:/ eellobiose have been investigated by stopped-flow spectrophotometr~,. Both FAD and home are reduced with a high rate constant at pH 4.2. in contrast, at pH 5.9, only FAD reduction is I'a~t, while the reduction of the heine is extremely slow. As a conclusion, the reduction of cytochrome c by CBO is dependent on heine, which functions at a lower pH range compared to reduction of FAD.

show abstract

Section: Discussionmentioning

confidence: 92%

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

1992

View full text Add to dashboard Cite

show abstract

“…In contrast to Morpeth's semiquinone suggestion [68], Wilson et al [85] identified the haem group as a candidate site. Later, the same group [63] redefined (for P. chrysosporium CDH) the relationships, arguing for the flavin as the site of oxygen reduction to superoxide, and the haem as a site of superoxide reduction to peroxide.…”

Section: Formation Of Reactive Oxygen Speciesmentioning

confidence: 97%

“…The haem group is bound in a pocket at one face of the β sandwich close to the surface of the molecule. The concave inner β sheet forms the framework of the pocket, and three loops protruding from this sheet wedge the protoporphyrin-IX ring, two from above (residues 62-68 and 148-161) and one from below (residues [85][86][87][88][89][90][91][92][93][94][95]. The packing of the pocket is tight with mainly hydrophobic residues, leaving little or no space for entry of additional molecules.…”

Section: Overall Structure Of the Cdh Cytochrome Domainmentioning

confidence: 99%

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

Zámocký¹,

Ludwig

Peterbauer

et al. 2006

CPPS

221

230

View full text Add to dashboard Cite

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.

show abstract

“…The haem then acts merely as a parking place for extra electrons when one‐electron acceptors oxidise the flavin (the ‘electron sink’ model). In contrast Wilson et al [12] suggested that even the two‐electron acceptor, oxygen, may actually react with the haem group rather than the flavin.…”

Section: Introductionmentioning

confidence: 99%

Oxygen reduction by cellobiose oxidoreductase: the role of the haem group

et al. 2002

View full text Add to dashboard Cite

We have used optical and electron paramagnetic spectroscopy to study the flavohaem enzyme cellobiose oxidoreductase (CBOR) from Phanerochaete chrysosporium. We have examined redox cycles of the enzyme in which the oxidation of cellobiose to cellobionolactone is coupled to the reduction of oxygen. During turnover flavin can reduce oxygen with one electron to produce superoxide or two electrons to produce hydrogen peroxide. Addition of superoxide dismutase significantly extended the time courses of these cycles, slowing the reoxidation rate of both cofactors. Addition of catalase also affected the haem time course, but to a lesser extent. Experiments in which superoxide was generated in the reaction mixture showed that this radical greatly enhanced the rate of haem re-oxidation. From these results we propose a mechanism in which reactive oxygen species generation by CBOR flavin subsequently re-oxidises CBOR haem. We discuss this mechanism in relationship to the biological function of this enzyme, namely lignocellulose degradation. ß 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

show abstract

Reactions of reduced cellobiose oxidase with oxygen. Is cellobiose oxidase primarily an oxidase?

Cited by 36 publications

References 4 publications

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

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

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

Oxygen reduction by cellobiose oxidoreductase: the role of the haem group

Contact Info

Product

Resources

About