Tentoxin-induced energy-independent adenine nucleotide exchange and ATPase activity with chloroplast coupling factor 1.
1. The effect of energy transfer inhibitors on energy-dependent exchange of tightly bound adenine nucleotides with washed, broken spinach thylakoids has been studied. Energy transfer inhibitors that inhibit the ATPase activity of soluble chloroplast coupling factor 1 (CF1) (e.g. phloridzin and tentoxin) do not inhibit energy-dependent adenine nucleotide exchange. Energy transfer inhibitors that block proton flux through the hydrophobic protein proton channel (CF0) (e.g. dicyclohexylcarbodiimide and triphenyltin chloride) also block light-dependent adenine nucleotide exchange. 2. Tentoxin, at relatively high concentrations, stimulates an energy-independent exchange of adenosine diphosphate. 3. High concentrations of tentoxin elicit a Ca2+-dependent ATPase activity with soluble CF1, but has no effect on the Ca2+-dependent ATPase activity of membrane-bound CF1. 4. The trypsin-activated, Ca2+-dependent, membrane-bound ATPase is not affected by high concentrations of tentoxin, whereas the dithiothreitol-activated, Mg2+-dependent ATPase is markedly inhibited. 5. The reconstitution of chloroplasts, partially depleted in CF1, with soluble CF1 is correlated with the loss of tentoxin-induced, Ca2+-dependent ATPase activity associated with soluble CF1.
D000227:Adenine Nucleotides / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004735:Energy Transfer; D007700:Kinetics; D009183:Mycotoxins / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010695:Phlorhizin / Q000494:pharmacology; D010944:Plants; D006180:Proton-Translocating ATPases / Q000378:metabolism*
D000227:Adenine Nucleotides; D009183:Mycotoxins; D010456:Peptides, Cyclic; D004024:Dicyclohexylcarbodiimide; D010695:Phlorhizin; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; D000252:Calcium-Transporting ATPases