Prolonged incubation with low concentrations of mercury alters energy transfer and chlorophyll (Chl)aprotein complexes inSynechococcus6301: changes in Chlaabsorption and emission characteristics and loss of the F695 emission band
✍ Scribed by S. D. S. Murthy; N. Mohanty; Prasanna Mohanty
- Book ID
- 104640228
- Publisher
- Springer Netherlands
- Year
- 1995
- Tongue
- English
- Weight
- 396 KB
- Volume
- 8
- Category
- Article
- ISSN
- 1572-8773
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✦ Synopsis
Synechococcus
PCC 6301 cells grown in the presence of low sublethal levels of (about 2 #M) mercury induced alterations in chlorophyll (Chl) a absorption without significant alterations in phycocyanin. Chl a fluorescence emission in Hg2+-raised cells showed a large (about 18 nm) blue shift in the peak emission. No major spectral changes in phycobilisome (PBsome) emission characteristic were noticed, indicating major structural alterations in Chl-protein complexes by incubation with Hg z § ions. Low temperature (77 K) emission spectra of cells grown in the presence of Hg 2+ showed a loss of the characteristic Chl a emission band at 695 nm (F695), which is known to be linked to photosystem II photochemistry and to originate from the Chl a of core antenna polypeptide CP 47 of photosystem II. The SDS-PAGE polypeptide profile of thylakoids indicates a loss of a polypeptide(s) with a molecular mass between 40 and 60 kDa by Hg 2+ incubation of cells. Our results suggest that prolonged incubation of Synechococcus 6301 cells with low concentrations of Hg 2+ affects the Chl a spectral properties and the structure of Chl-protein complexes.