RT Journal Article
T1 Two-step oxidation of glycerol to glyceric acid catalyzed by the Phanerochaete chrysosporium glyoxal oxidase
A1 Roncal, Tomás
A1 Muñoz, Carmen
A1 Lorenzo, Leire
A1 Maestro, Belén
A1 Díaz de Guereñu, María del Mar
AB Glyoxal oxidase of P. chrysosporium is a radical copper oxidase that catalyzes oxidation of aldehydes to carboxylic acids coupled to dioxygen reduction to H 2O 2. In addition to known substrates, glycerol is also found to be a substrate for glyoxal oxidase. During enzyme turnover, glyoxal oxidase undergoes a reversible inactivation, probably caused by loss of the active site free radical, resulting in short-lasting enzyme activities and undetectable substrate conversions. Enzyme activity could be extended by including two additional enzymes, horseradish peroxidase and catalase, in addition to a redox chemical activator, such as Mn(III) (or Mn(II)+H 2O 2) or hexachloroiridate. Using this three-enzyme system glycerol was converted in glyceric acid in a two-step reaction, with glyceraldehyde as intermediate. A possible operation mechanism is proposed in which the three enzymes would work coordinately allowing to maintain a sustained glyoxal oxidase activity. In the course of its catalytic cycle, glyoxal oxidase alternates between two functional and interconvertible reduced and oxidized forms resulting from a two-electron transfer process. However, glyoxal oxidase can also undergo an one-electron reduction to a catalytically inactive form lacking the active site free radical. Horseradish peroxidase could use glyoxal oxidase-generated H 2O 2 to oxidize Mn(II) to Mn(III) which, in turn, would reoxidize and reactivate the inactive form of glyoxal oxidase. Catalase would remove the excess of H 2O 2 generated during the reaction. In spite of the improvement achieved using the three-enzyme system, glyoxal oxidase inactivation still occurred, which resulted in low substrate conversions. Possible causes of inactivation, including end-product inhibition, are discussed.
SN 0141-0229
YR 2012
FD 2012-02-10
LK https://hdl.handle.net/11556/4286
UL https://hdl.handle.net/11556/4286
LA eng
NO Roncal , T , Muñoz , C , Lorenzo , L , Maestro , B & Díaz de Guereñu , M D M 2012 , ' Two-step oxidation of glycerol to glyceric acid catalyzed by the Phanerochaete chrysosporium glyoxal oxidase ' , Enzyme and Microbial Technology , vol. 50 , no. 2 , pp. 143-150 . https://doi.org/10.1016/j.enzmictec.2011.11.007
NO We are gratefully acknowledged to Dr. Daniel Cullen (USDA Forest Products Laboratory, Madison, Wisconsin, USA) for providing the P. chrysosporium glyoxal oxidase cDNA clone. We thank the Department of Industry, Trade and Tourism of the Basque Government for financial support of this project through the SAIOTEK program ( S-PE07LE03 ). Funding to C.M. under a grant of the Iñaki Goenaga Foundation is also acknowledged.
DS TECNALIA Publications
RD 31 jul 2024