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Formation of octadecadienoate dimers by soybean lipoxygenases
Author(s) -
Heijdt Lambertus M.,
Lecq Fridolin,
Lachmansingh Anand,
Versluis Kees,
Kerkvan Hoof Anca,
Veldink Gerrit A.,
Vliegenthart Johannes F. G.
Publication year - 1993
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02536230
Subject(s) - chemistry , linoleic acid , lipoxygenase , derivatization , chromatography , regioselectivity , radical , organic chemistry , gas chromatography , fatty acid , mass spectrometry , enzyme , catalysis
The aim of this investigation was to determine whether the regioselectivity found for lipoxygenases in the formation of fatty acid hydroperoxides from linoleic acid is reflected in the formation of dimeric products in secondary reactions involving linoleic acid, product hydroperoxide and lipoxygenase. A method was therefore developed for the separation and identification of dimers formed by fusion of two linoleic acid radicals or a linoleic acid radical and linoleate. The method includes solid‐phase extraction, preparative separation of products by thin‐layer chromatography, derivatization to the corresponding fully hydrogenated methyl esters and capillary gas chromatography (GC) coupled with electron impact mass spectrometry. We present evidence that the formation of octadecadienoate dimers, during the secondary reaction of soybean lipoxygenase‐1 or lipoxygenase‐3, is a nonenzymic process that can be envisaged by nonspecific association of intermediate fatty acid radicals (L * ) that have dissociated from the enzyme. We could show that the relative amounts of different octadecadienoate dimers formed remain unaltered, regard‐less of pH and type of soybean isoenzyme used. Quantitative analysis by GC showed that under the reaction conditions used, the formation of dimers branching at the 13‐position is preferred.