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Hg(2+) reacts with different components of the NADPH : protochlorophyllide oxidoreductase macrodomains.
- Source :
-
Plant biology (Stuttgart, Germany) [Plant Biol (Stuttg)] 2004 May; Vol. 6 (3), pp. 358-68. - Publication Year :
- 2004
-
Abstract
- The molecular background of Hg (2+)-induced inhibition of protochlorophyllide (Pchlide) photoreduction was investigated in homogenates of dark-grown wheat leaves. Our earlier work showed that 15 min incubation with 10 (-2) M Hg (2+) completely inhibits the activity of NADPH : Pchlide oxidoreductase ( ). Detailed analysis of spectra recorded at 10 K indicated the appearance of emission bands at 638 and 650 nm, which are characteristic for NADP (+)-Pchlide complexes. Fluorescence emission spectra recorded with different excitation wavelengths, fluorescence lifetime measurements and the analysis of acetone extractions revealed that Hg (2+) can also react directly with Pchlide, resulting in protopheophorbide formation. At 10 (-3) M Hg (2+), the phototransformation was complete but the blue shift of the chlorophyllide emission band speeded up remarkably. This indicates oxidation of the NADPH molecules that have a structural role in keeping together the etioplast inner membrane components. We suggest a complex model for the Hg (2+) effect: depending on concentration it can react with any components of the NADPH : Pchlide oxidoreductase macrodomains.
- Subjects :
- Environmental Pollutants pharmacology
Oxidoreductases Acting on CH-CH Group Donors antagonists & inhibitors
Photosynthesis drug effects
Plant Leaves drug effects
Triticum drug effects
Mercury pharmacology
Oxidoreductases Acting on CH-CH Group Donors metabolism
Photosynthesis physiology
Plant Leaves enzymology
Triticum enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 1435-8603
- Volume :
- 6
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Plant biology (Stuttgart, Germany)
- Publication Type :
- Academic Journal
- Accession number :
- 15143445
- Full Text :
- https://doi.org/10.1055/s-2004-817893