title: Novel allene oxide synthase products formed via Favorskii-type rearrangement: mechanistic implications for 12-oxo-10,15-phytodienoic acid biosynthesis.
abstract: The allene oxide synthase (AOS) pathway is widespread in plants. Its products, such as cyclopentenone 12-oxo-10,15-phytodienoic acid (12-oxo-PDA) and related jasmonates, play important biological roles in plants. We found that 12-oxo-PDA in some plant tissues co-occur with an unknown minor oxylipin 1. In vitro incubations of AOSs with α-linolenic acid 13(S)-hydroperoxide reliably afforded 1 along with 12-oxo-PDA and α-ketol. A similar oxylipin 3 was formed during the AOS conversions of γ-linolenic acid 9(S)-hydroperoxide. Linoleic acid hydroperoxides formed neither products similar to 1 and 3 nor cyclopentenones. Oxylipins 1 and 3 were purified and identified as the products of Favorskii-type rearrangement, (2'Z,4Z)-2-(2'-pentenyl)-4-tridecene-1,13-dioic acid and (2'Z,4Z)-2-(2'-octenyl)-4-decene-1,10-dioic acid, respectively. Detection of Favorskii products 1 and 3 demonstrates that cyclopropanones are short-lived AOS products along with allene oxides. The observed parallels between the Favorskii product 1 and 12-oxo-PDA formation suggests that cyclopropanone is either a byproduct or a precursor of 12-oxo-PDA.
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, Kazan, Russia. grechkin@mail.knc.ru
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Grechkin
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Lantsova
authors.forename: Yana Y
authors.initials: YY
authors.lastname: Toporkova
authors.forename: Svetlana S
authors.initials: SS
authors.lastname: Gorina
authors.forename: Faina K
authors.initials: FK
authors.lastname: Mukhitova
authors.forename: Boulat I
authors.initials: BI
authors.lastname: Khairutdinov
mesh_terms: D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000737:chemistry; D019746:Intramolecular Oxidoreductases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D054883:Oxylipins / Q000138:chemical synthesis* / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: C570211:(2'Z,4Z)-2-(2'-octenyl)-4-decene-1,10-dioic acid; C570210:(2'Z,4Z)-2-(2'-pentenyl)-4-tridecene-1,13-dioic acid; D005231:Fatty Acids, Unsaturated; D054883:Oxylipins; C025999:12-oxophytodienoic acid; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase