chlorophyll-a and triphenyltin-chloride

The effect of the organometallic compounds containing lead, (C6H5)3PbCl , and tin, (C6H5)3SnCl, on Chlorella green algae photosystem II was studied. Suspension of the algae treated with (C6H5)3SnCl at concentrations of 1.0 and 4.0 micromol dm(-3) for 22 h revealed a decrease in most physiological parameters studied, particularly in decasecond component of delayed chlorophyll luminescence, photosynthetic electron transport rate and diluted oxygen concentration, which implies an inhibition of photosynthetic electron transport as well as oxygen evolving system. On the other hand, (C6H5)3PbCl caused stronger inhibition than (C6H5)3SnCl, particularly in the higher concentration.

Topics: Chlorella vulgaris; Chlorophyll; Electron Transport; Kinetics; Lead; Luminescence; Organometallic Compounds; Organotin Compounds; Oxygen; Photosystem II Protein Complex; Tin Compounds

Spirulina subsalsa is immobilized with alginate, which increases the growth rate, chlorophyll content, phycocyanin content and nitrate reductase activity. Immobilized Spirulina subsalsa with alginate increases absorption of triphenyltin chloride (TPT). The phycocyanin of immobilized Spirulina subsalsa is more sensitive to TPT then free alga. The immobilization enhances the toxic effect of TPT on nitrate reductase activity of Spirulina subsalsa. Experimental results demonstrate that the immobilization of Spirulina subsalsa is feasible. Removal of TPT by immobilized Spirulina subsalsa reaches 68%. Biosorption mechanism of TPT by Spirulina subsalsa should be further studied.

Topics: Absorption; Alginates; Chlorophyll; Cyanobacteria; Glucuronic Acid; Hexuronic Acids; Nitrate Reductase; Nitrate Reductases; Organotin Compounds; Phycocyanin; Water; Water Pollutants, Chemical

Topics: Cell Count; Chlorophyll; Culture Media; Eukaryota; Fresh Water; Kinetics; Organotin Compounds; Water Pollutants, Chemical

The induction of millisecond delayed fluorescence mediated by PS I-dependent proton pumping has been used as an indicator of the time course with which those protons equilibrate with sites on the oxygen-evolving enzyme complex (Bowes, J. M., and Crofts, A. R. (1978). Z. Naturforsch. 33C, 271-275). We found that the induction curves were retarded by a reversible exposure of non-energized thylakoids to low concentrations of the uncoupler, desaspidin, at alkaline, but not at neutral, pH. The induction curves were not retarded by increasing the buffering capacity of the thylakoid lumen with Tricine, and were inhibited by the energy transfer inhibitors, dicyclohexylcarbodiimide (DCCD) and triphenyltin chloride (TPT). These data suggest that the catalytic site of the water-splitting complex is located in proton-sequestering membrane domains, rather than at the lumen-exposed inner membrane surface, protons released during PS I-mediated electron transport might equilibrate with protonatable sites on the oxygen-evolving complex without passing through the lumen, and those protons may travel over specific conducting pathways which can be blocked by DCCD and TPT.

Topics: Chlorophyll; Dicyclohexylcarbodiimide; Electron Transport; Fluorescence; Kinetics; Light-Harvesting Protein Complexes; Organotin Compounds; Oxidoreductases; Oxygen; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Photosystem II Protein Complex; Plant Proteins; Protons; Time Factors

At very low concentrations (less than 1 muM) triphenyltin chloride inhibits ATP formation and coupled electron transport in isolated spinach chloroplasts. Basal (-Pi) and uncoupled electron transport are not affected by triphenyltin. The membrane-bount ATP in equilibrium Pi exchange and Mg2+-dependent ATPase activities of chloroplasts are also completely sensitive to triphenyltin, although the Ca2+-dependent and Mg2+-dependent ATPase activities of the isolated coupling factor protein are insensitive to triphenyltin. The light-driven proton pump in chloroplasts is stimulated (up to 60%) by low levels of triphenyltin. Indeed, the amount of triphenyltin necessary to inhibit ATP formation or stimulate proton uptake is dependent upon the amount of chloroplasts present in the reaction mixture, with an apparent stoichiometry of 2-2.5 triphenyltin molecules/100 chlorophyll molecules at 50% inhibition of ATP formation and half-maximal stimulation of proton uptake. Chloroplasts partially stripped of coupling factor by an EDTA was are no longer able to accumulate protons in the light. However, low levels of triphenyltin can effectively restore this ability. The amount of triphenyltin required for the restoration of net proton uptake is also dependent upon the amount of chloroplasts, with a stoichiometry of 4-5 triphenyltin molecules/100 chlorophyll molecules at 50% reconstitution. On the basis of this and other evidence it is concluded that triphenyltin chloride inhibits phosphorylation, ATP + Pi exchange and membrane-bound ATPase activities in chloroplasts by specifically blocking the transport of protons through a membrane-bound carrier or channel located in a hydrophobic region of the membrane at or near the functional binding site for the coupling factor.

Topics: Adenosine Triphosphatases; Adenosine Triphosphate; Binding Sites; Cell Membrane; Chlorophyll; Chloroplasts; Dithiothreitol; Edetic Acid; Electron Transport; Enzyme Activation; Kinetics; Light; Magnesium; Organotin Compounds; Phosphates; Photophosphorylation; Plants