1 / 6

Sea water: High tide

Particle formation. IO •. XAS. I -. h n. O 3. I 2. I -. I -. I -. Iodine uptake V-haloperoxidase. H 2 O 2 / ROS. I -. Sea water: High tide. Atmosphere: Low tide. I•. I -. I -. Biological significance: Iodine accumulation in Laminaria.

dieter-stuart
Download Presentation

Sea water: High tide

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Particle formation IO• XAS I- hn O3 I2 I- I- I- Iodine uptakeV-haloperoxidase H2O2 / ROS I- Sea water: High tide Atmosphere: Low tide I• I- I-

  2. Biological significance: Iodine accumulation in Laminaria • Laminaria accumulates iodide as an inorganic antioxidant: the first case in a living system! • Other, previous hypotheses: chemical defense (grazers, pathogens) • Implications for atmospheric & marine chemistry

  3. Biological significance: Iodine accumulation in Laminaria • Iodo(hydro)carbons: quantitatively insignificant as H2O2 scavenging products • Must have another function – defense?! • Iodine is a better leaving group than bromine or chlorine:I > Br > Cl => High reactivity / strong alkylating potential of iodinated compounds

  4. What makes iodide a suitable antioxidant? • Reactions with major oxidants (H2O2, O2-, OH., 1O2) are very favourable kinetically and thermodynamically • Iodide compares well with established, organic biological antioxidants • Iodide is the only halide with potential antioxidant properties • Confirmed in a heterologous system: iodide quenches respiratory burst in human blood (IC50 = 2.9 mM)

  5. Cell wall (apoplast) Sea water Ascorbate, glutathione, etc. Cell / cytosol I- Complementarity to other antioxidant systems • Iodide is an apoplastic antioxidant (i.e. limited to the cell wall space) • Ascorbate and glutathione are strictly intracellular (not excreted / effluxed) • EST data suggest that Laminaria has fewer and lower expression levels of typical antioxidant enzymes than other eukaryotes

  6. Iodine accumulation in Laminaria Küpper FC, Carpenter LJ, McFiggans GB, Palmer CJ, Waite T, Boneberg E-M, Woitsch S, Weiller M, Abela R, Grolimund D, Potin P, Butler A, Luther III GW, Kroneck PMH, Meyer-Klaucke W, Feiters MC, 2008: Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry.- Proceedings of the National Academy of Sciences of the USA 105 (19), 5954-58

More Related