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

FEBS Letters

Ball, Andrew¹  Mason, Maria G.¹  Wilson, Michael T.¹  Nicholls, Peter¹ 

[1] Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK

关键词: Cellobiose dehydrogenase;    Oxidoreductase;    Oxygen;    Superoxide;    Peroxide;    Cellulose degradation;    Lignin;    Reactive oxygen species;    Phanerochaete chrysosporium;    CBOR;    cellobiose dehydrogenase (oxidoreductase);    SOD;    superoxide dismutase;    XO;    xanthine oxidase;    ROS;    reactive oxygen species;    GOX;    glucose oxidase;   

DOI  :  10.1016/S0014-5793(02)02633-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 re-oxidation 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.

【 授权许可】

Unknown