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Allene oxide synthase from Arabidopsis thaliana (CYP74A1) exhibits dual specificity that is regulated by monomer‐micelle association
Author(s) -
Hughes Richard K.,
Belfield Eric J.,
Ashton Ruth,
Fairhurst Shirley A.,
Göbel Cornelia,
Stumpe Michael,
Feussner Ivo,
Casey Rod
Publication year - 2006
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.2006.06.075
Subject(s) - micelle , arabidopsis thaliana , chemistry , monomer , atp synthase , cytochrome p450 , kinetics , arabidopsis , enzyme , substrate (aquarium) , biochemistry , biophysics , stereochemistry , mutant , biology , organic chemistry , ecology , physics , quantum mechanics , aqueous solution , gene , polymer
We investigate the effects of detergent on the kinetics and oligomeric state of allene oxide synthase (AOS) from Arabidopsis thaliana (CYP74A1). We show that detergent‐free CYP74A1 is monomeric and highly water soluble with dual specificity, but has relatively low activity. Detergent micelles promote a 48‐fold increase in k cat / K m (to 5.9 × 10 7 M −1 s −1 ) with concomitant changes in the spin state equilibrium of the haem‐iron due to the binding of a single detergent micelle to the protein monomer, which is atypical of P450 enzymes. This mechanism is shown to be an important determinant of the substrate specificity of CYP74A1. CYP74A1 may be suited for structural resolution of the first plant cytochrome P450 and its 9‐AOS activity and behaviour in vitro has implications for its role in planta .