- PpoC from Aspergillus nidulans is a fusion protein with only one active haem
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In Aspergillus nidulans Ppos [psi (precocious sexual inducer)-producing oxygenases] are required for the production of so-called psi factors, compounds that control the balance between the sexual and asexual life cycle of the fungus. The genome of A. nidulans harbours three different ppo genes: ppoA, ppoB and ppoC. For all three enzymes two different haem-containing domains are predicted: a fatty acid haem peroxidase/ dioxygenase domain in the N-terminal region and a P450 haem-thiolate domain in the C-terminal region. Whereas PpoA was shown to use both haem domains for its bifunctional catalytic activity (linoleic acid 8-dioxygenation and 8-hydroperoxide isomerization), we found that PpoC apparently only harbours a functional haem peroxidase/dioxygenase domain. Consequently, we observed that PpoC catalyses mainly the dioxygenation of linoleic acid (18:2Δ 9Z,12Z), yielding 10-HPODE (10-hydroperoxyoctadecadienoic acid). No isomerase activity was detected. Additionally, 10-HPODE was converted at lower rates into 10-KODE (10-keto-octadecadienoic acid) and 10-HODE (10-hydroxyoctadecadienoic acid). In parallel, decomposition of 10-HPODE into 10-ODA (10-octadecynoic acid) and volatile C-8 alcohols that are, among other things, responsible for the characteristic mushroom flavour. Besides these principle differences we also found that PpoA and PpoC can convert 8-HPODE and 10-HPODE into the respective epoxy alcohols: 12,13-epoxy-8-HOME (where HOME is hydroxyoctadecenoic acid) and 12,13-epoxy-10-HOME. By using site-directed mutagenesis we demonstrated that both enzymes share a similar mechanism for the oxidation of 18:2Δ9Z,12Z; they both use a conserved tyrosine residue for catalysis and the directed oxygenation at the C-8 and C-10 is most likely controlled by conserved valine/leucine residues in the dioxygenase domain. The Authors Journal compilation
- Brodhun, Florian,Schneider, Stefan,Goebel, Cornelia,Hornung, Ellen,Feussner, Ivo
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experimental part
p. 553 - 565
(2011/02/23)
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- A NEW ROUTE FOR THE SYNTHESIS OF 10-HYDROXYDEC-2E-ENOIC AND DEC-2E-ENEDIOIC ACIDS
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A new simple route for the synthesis of 10-hydroxydec-2E-enoic and dec-2E-enedioic acids from cycloocta-1Z,5Z-diene has been developed.
- Odinokov, V. N.,Ishmuratov, G. Yu.,Tolstikov, G. A.
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p. 658 - 660
(2007/10/02)
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- A NOVEL SYNTHESIS OF ROYAL JELLY ACIDS AND QUEEN SUBSTANCE BY THE FIVE CARBON HOMOLOGATION USING β-VINYL-β-PROPIOLACTONE
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10-Hydroxy-(E)-2-decenoic acid, (E)-2-decenedioic acid (Royal jelly acids), and 9-oxo-(E)-2-decenoic acid (queen substance) were synthesized via 10-hydroxy-3-decenoic acid and 9,9-ethylenedioxy-3-decenoic acid, respectively, prepared easily by the regioselective ring-opening reaction of β-vinyl-β-propiolactone with Grignard reagents in the presence of copper(I) catalyst.
- Fujisawa, Tamotsu,Sato, Toshio,Itoh, Toshiyuki
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p. 219 - 220
(2007/10/02)
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