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Regio‐ and Stereospecificity in the Oxygenation of Arachidonic Acid Catalyzed by Leu597 Mutants of Rabbit 15‐Lipoxygenase: A QM/MM Study
Author(s) -
Suardíaz Reynier,
Masgrau Laura,
Lluch José M.,
GonzálezLafont Àngels
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402045
Subject(s) - molecular mechanics , chemistry , arachidonic acid , stereospecificity , stereochemistry , mutant , qm/mm , lipoxygenase , catalysis , wild type , molecular dynamics , cyclooxygenase , enzyme , computational chemistry , biochemistry , gene
We combined quantum mechanics/molecular mechanics calculations with molecular dynamics simulations to study the addition of O 2 to the pentadienyl radical of arachidonic acid (AA) catalyzed by the Leu597Val and Leu597Ala mutants of rabbit 15‐lipoxygenase (15‐rLO). In the Leu597Val mutant, the addition of O 2 to C15 of AA is the predominant path, although it reduces the C15/C11 product ratio by almost ten times with respect to the wildtype enzyme. The S stereochemistry is kept. Mutation to Ala causes just the opposite effect: regiospecificity favoring addition to C15 is somewhat sharper than that in the wildtype, but the stereochemistry is R . This is because the extra space created by the mutation to Ala is big enough for AA to move so that it can adopt an alternative binding mode, and this opens new feasible paths for the attack of O 2 . So, we showed that the Leu597Ala mutant of 15r‐LO works as an aspirin‐acetylated cyclooxygenase‐2, which makes 15‐( R )‐ hydroperoxyeicosatetraenoic acid.