Mercury ions inhibit photosynthetic electron transport at multiple sites in the cyanobacteriumSynechococcus 6301 |
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Authors: | S D S Murthy Prasanna Mohanty |
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Institution: | (1) School of Life Sciences, Jawaharlal Nehru University, 110 067 New Delhi, India |
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Abstract: | Inhibition of electron transport activities in the spheroplasts ofSynechococcus 6301 by HgCl2 is dependent on the concentration of mercury ions. The inhibition of whole chain electron transport activity occurs at low
concentration of Hg2+ (6 ΜM@#@). This inhibition occurs mostly due to interaction of Hg2+ on plastocyanin. At an elevated concentration (24 ΜM@#@), mercury induces inhibition chiefly in photosystem II catalyzed electron transport. At this concentration it also alters
both the absorption and emission characteristics of the phycocyanin. The photosystem I catalyzed electron transport was inhibited
by 50% only at high concentrations (36 ΜM@#@) of HgCl2. However, electron transport catalyzed by photosystems I and II from reduced duroquinone to methylviologen which involves
intersystem electron transport is extremely sensitive to mercury (low concentration 6–9 ΜM) like that of whole chain assay
indicating that the observed inhibition in whole chain electron transport at low concentrations is mostly contributed by the
damage involving other intersystem electron transport carrier(s) like plastocyanin. Thus mercury ions depending on the concentration
affects the electron transport at multiple sites in the spheroplasts ofSynechococcus. |
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Keywords: | Electron transport mercury phycocyanin sepheroplasts Synechococcus 6301 |
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