Positional- and stereo-selectivity of fatty acid oxygenation catalysed by mouse (12S)-lipoxygenase isoenzymes.
A quantitative stereochemical analysis of the products generated by recombinant mouse (12S)-lipoxygenase isoenzymes was performed with arachidonic acid and linoleic acid as substrates. The leucocyte-type (12S)-lipoxygenase generated, in addition to 12-hydroxyeicosatetraenoic acid (12-HETE) as the main product, 15- and 8-HETE from arachidonic acid and 13- and 9-hydroxyoctadecadienoic acid (13- and 9-HODE) from linoleic acid. The platelet-type enzyme oxygenated arachidonic acid to 12- and 8-HETE and linoleic acid to 13- and 9-HODE, whereas the epidermis-type (12S)-lipoxygenase reaction was essentially mono-specific with arachidonic acid but oxygenated linoleic acid to both 13- and 9-HODE. 12-HETE and 13-HODE were almost exclusively the S enantiomers. 8-HETE was the R enantiomer as a side-product of the platelet-type (12S)-lipoxygenase reaction but the S enantiomer as a side-product of the leucocyte-type reaction. 9-HODE was generated as the R enantiomer by the platelet-type and the epidermis-type isoenzymes and as the S enantiomer by the leucocyte-type (12S)-lipoxygenase. On the basis of published models of lipoxygenase-substrate interaction, the stereochemistry of the products generated by the platelet- and epidermis-type (12S)-lipoxygenases is in agreement with a fixed 'tail-to-head' orientation of the substrate fatty acid in the binding pocket of these enzymes, whereas that of the reaction products of the leucocyte-type (12S)-lipoxygenase can be explained only when the inverse orientation of the substrate or a rotational isomerism along the longitudinal axis of the substrate is allowed. Both the product spectra generated and the sensitivity towards the 12-lipoxygenase selective inhibitors N-benzyl-N-hydroxy-4-phenylpentanamide and cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate indicated the platelet-type and the epidermis-type isoenzymes to be biochemically more related to each other than to the leucocyte-type (12S)-lipoxygenase.
Bürger
F
F
Research Program Tumor Cell Regulation (B0500), Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
Krieg
P
P
Marks
F
F
Fürstenberger
G
G
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology; D002460:Cell Line; D004817:Epidermis / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology; D008041:Linoleic Acids / Q000378:metabolism; D044243:Linoleic Acids, Conjugated; D051379:Mice; D008956:Models, Chemical; D011994:Recombinant Proteins / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity; D014162:Transfection
D007527:Isoenzymes; D008041:Linoleic Acids; D044243:Linoleic Acids, Conjugated; D011994:Recombinant Proteins; C024347:9-hydroxy-10,12-octadecadienoic acid; D016718:Arachidonic Acid; C024348:13-hydroxy-9,11-octadecadienoic acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D001092:Arachidonate 12-Lipoxygenase