On the singular, dual, and multiple positional specificity of manganese lipoxygenase and its G316A mutant
2007 (English)In: Journal of Lipid Research, ISSN 0022-2275, E-ISSN 1539-7262, Vol. 48, no 4, 890-903 p.Article in journal (Refereed) Published
Manganese lipoxygenase (Mn-LO) oxygenates 18:3n-3 and 18:2n-6 to bis-allylic 11S-hydroperoxy fatty acids, which are converted to 13R-hydroperoxy fatty acids. Other unsaturated C16-C22 fatty acids, except 17:3n-3, are poor substrates, possibly due to ineffective enzyme activation (MnIIMnIII) by produced hydroperoxides. Our aim was to determine whether unsaturated C16-C22 fatty acids were oxidized by MnIII-LO. MnIII-LO oxidized C16, C19, C20, and C22 n-3 and n-6 fatty acids. The carbon chain length influenced the position of hydrogen abstraction (n-8, n-5) and oxygen insertion at the terminal or the penultimate 1Z,4Z-pentadienes. Dilinoleoyl¬glycero¬phosphatidyl¬¬choline was oxidized by Mn-LO in agreement with a “tail first” model. 16:3n-3 was oxidized at the bis-allylic n-5 carbon and at positions n-3, n-7, and n-6. Long fatty acids, 19:3n-3, 20:3n-3, 20:4n-6, 22:5n-3, and 22:5n-6, were mainly oxidized at the n-6 and the bis-allylic n-8 positions (in ratios of ~3:2). The bis-allylic hydroperoxides accumulated with one exception, 13-hydroperoxyeicosatetraenoic acid (13-HPETE). MnIII-LO oxidized 20:4n-6 to 15R-HPETE (~60%) and 13-HPETE (~37%) and converted 13-HPETE to 15R-HPETE. MnIII-LO G316A mainly oxygenated 16:3n-3 at positions n-7 and n-6, 19:3n-3 at n-10, n-8, and n-6, 20:3n-3 at n-10 and n-8. We conclude that Mn-LO likely binds fatty acids “tail first” and oxygenates many C16, C18, C20 and C22 fatty acids to significant amounts of bis-allylic hydroperoxides.
Place, publisher, year, edition, pages
2007. Vol. 48, no 4, 890-903 p.
nonconjugated peroxyls, fatty acid oxygenation, hydroperoxide isomerase, mass spectrometry, metalloenzymes, dilinoleoyl-glycerophosphatidylcholine, thermostability
IdentifiersURN: urn:nbn:se:uu:diva-23690DOI: 10.1194/jlr.M600505-JLR200ISI: 000245627100015PubMedID: 17259599OAI: oai:DiVA.org:uu-23690DiVA: diva2:51464