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Critical amino acids for the 8( R )‐dioxygenase activity of linoleate diol synthase. A comparison with cyclooxygenases
Author(s) -
Garscha Ulrike,
Oliw Ernst H.
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2008.09.031
Subject(s) - dioxygenase , histidine , biochemistry , chemistry , stereochemistry , isomerase , site directed mutagenesis , heme , residue (chemistry) , enzyme , mutagenesis , tyrosine , amino acid , mutation , mutant , gene
7,8‐Linoleate diol synthase (7,8‐LDS) of the take‐all fungus and cyclooxygenases can be aligned with ∼24% amino acid identity and both form a tyrosyl radical during catalysis. 7,8‐LDS was expressed in insect cells with native 8 R ‐dioxygenase and hydroperoxide isomerase activities. We studied conserved residues of 7,8‐LDS, which participate in cyclooxygenases for heme binding (His residues), hydrogen abstraction (Tyr), positioning (Tyr, Trp), and ionic binding of substrates (Arg). Site‐directed mutagenesis abolished 8 R ‐dioxygenase activities with exception of the putative distal histidine (His203Gln) and a tyrosine residue important for hydrogen bonding and substrate positioning (Tyr329Phe). The results demonstrate structural similarities between 7,8‐LDS and cyclooxygenases.