|Gene:||lipI||Accession Number: G-10937 (MetaCyc)|
Species: Phanerochaete chrysosporium
lignin peroxidases (LiPs) are monomeric hemoproteins with molecular masses around 40 kDa, and resemble classical peroxidases in that their Fe3+ is pentacoordinated to the four heme tetrapyrrole nitrogens and to a histidine residue. Like the classical peroxidases, LiPs are oxidized by hydrogen peroxide to give a two electron-oxidized intermediate (known as Compound I) in which the iron is present as Fe+4 and a free radical resides on the tetrapyrrole ring. Compound I then oxidizes a donor substrate by one electron, yielding a substrate-free radical and Compound II, in which the iron is still present as Fe+4, but no radical is present on the tetrapyrrole. The process continues when Compound II oxidizes a second molecule of donor substrate, giving another substrate-free radical and restoring the resting state of the peroxidase. Unlike classical peroxidases, LiPs can oxidize aromatic rings that are only moderately activated by electron-donating substituents, such as the major nonphenolic structures of lignin [Hammel08].
An important feature in LiPs is an invariant tryptophan residue - trp171 in the isozyme termed LiPA, which is thought to participate in longrange electron transfer from aromatic substrates that cannot make direct contact with the oxidized heme [Doyle98].
Locations: extracellular space
|Cellular Component:||GO:0005576 - extracellular region|
Enzymatic reaction of: lignin peroxidase
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Reversibility of this reaction is unspecified.
Doyle98: Doyle WA, Blodig W, Veitch NC, Piontek K, Smith AT (1998). "Two substrate interaction sites in lignin peroxidase revealed by site-directed mutagenesis." Biochemistry 37(43);15097-105. PMID: 9790672
Gaskell94: Gaskell J, Stewart P, Kersten PJ, Covert SF, Reiser J, Cullen D (1994). "Establishment of genetic linkage by allele-specific polymerase chain reaction: application to the lignin peroxidase gene family of Phanerochaete chrysosporium." Biotechnology (N Y) 12(13);1372-5. PMID: 7765568
©2014 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493