Exploring the hydroxylation-dehydrogenation connection: novel catalytic activity of castor stearoyl-ACP Delta(9) desaturase.
The novel product profile obtained by incubating chiral fluorinated substrate analogues with castor stearoyl-ACP Delta(9) desaturase has been rationalized through a series of labeling studies. It was found that the introduction of the Z-double bond between C-9 and C-10 of the parent substrate occurs with pro-R enantioselectivity--a result that accounts for the observed stereochemistry of oxidation products derived from (9R)- and (9S)-9-fluorostearoyl-ACP. Oxidation of (9R)-9-fluorostearoyl-ACP occurs via at least two rapidly interchanging substrate conformations in the active site as detected by reaction pathway branching induced by deuteration at C-10 and C-11. Hydroxylation and desaturation of this substrate share the same site of initial oxidative attack.
Behrouzian
Behnaz
B
Department of Biology, Brookhaven National Laboratory, Upton, NY 11973, USA.
Savile
Christopher K
CK
Dawson
Brian
B
Buist
Peter H
PH
Shanklin
John
J
D000213:Acyl Carrier Protein / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry / Q000378:metabolism; D006900:Hydroxylation; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000378:metabolism*; D008968:Molecular Conformation
D000213:Acyl Carrier Protein; D006845:Hydrocarbons, Fluorinated; D006899:Mixed Function Oxygenases; C018747:acyl-(acyl-carrier-protein)desaturase