title: Stereochemistry of Delta4 dehydrogenation catalyzed by an ivy (Hedera helix) Delta9 desaturase homolog.
abstract: The stereochemistry of palmitoyl-ACP Delta(4) desaturase-mediated dehydrogenation has been examined by tracking the fate of deuterium atoms located on stereospecifically monodeuterated substrates-(4S)- and (4R)-[4-(2)H(1)]-palmitoyl-ACP and (5S)- and (5R)-[5-(2)H(1)]-palmitoyl-ACP. It was found that the introduction of the (Z)-double bond between C-4 and C-5 of a palmitoyl substrate occurs with pro-R enantioselectivity-a result which matches that obtained for a closely related homolog-castor stearoyl-ACP Delta(9) desaturase. These data show that despite the difference in regioselectivity between the two enzymes, the stereochemistry of hydrogen removal is conserved.
authors.affiliation: Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Tremblay
authors.forename: Edward
authors.initials: E
authors.lastname: Whittle
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buist
authors.forename: John
authors.initials: J
authors.lastname: Shanklin
mesh_terms: D002384:Catalysis; D035981:Hedera / Q000201:enzymology*; D006865:Hydrogenation; D015394:Molecular Structure; D010168:Palmitates / Q000138:chemical synthesis* / Q000737:chemistry; D013230:Stearoyl-CoA Desaturase / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D010168:Palmitates; D013230:Stearoyl-CoA Desaturase