Inhibition of membrane-bound chloroplast coupling factor 1 by a dephosphorylated derivative of dialdehyde ADP.
Periodate-oxidized ADP, if left in aqueous solution, loses its phosphates by beta-elimination. This dephosphorylated dialdehyde compound caused rapid and irreversible inhibition of membrane-bound spinach chloroplast coupling factor 1 (CF1). Inhibition was 2.5 times faster in the light than in the dark. A high concentration of uncoupler eliminated the light stimulation. Light could be replaced by an acid-base transition. Therefore, the dialdehyde reacts with a site or sites on CF1 that become exposed by a high-energy state-induced conformational change. The substrate nucleotides ADP, ATP, GDP, and GTP protected against inhibition while Pi and the non-substrate nucleotides AMP, GMP, CTP, and UTP did not. The protection by GTP was competitive and magnesium-dependent, suggesting that the dialdehyde binds to a nucleotide-binding site. However, the corresponding UDP and CDP dialdehyde derivatives also inhibited CF1 and showed the light-stimulation effect, indicating that the adenine is not important for the binding. These derivatives could be binding to a nucleotide-binding site or to another reactive site that becomes exposed during the light-induced conformational change. In the latter case the protection by substrate nucleotides would be due to prevention of the energy-dependent conformational change.
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Garbarino
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Jagendorf
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology; D006096:Gramicidin / Q000494:pharmacology; D008027:Light; D008274:Magnesium / Q000494:pharmacology; D009711:Nucleotides / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism; D010944:Plants / Q000201:enzymology*; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors*; D013997:Time Factors
D009711:Nucleotides; D010710:Phosphates; D000643:Ammonium Chloride; D006096:Gramicidin; D000244:Adenosine Diphosphate; C018808:adenosine 5'-diphosphate 2',3'-dialdehyde; D006180:Proton-Translocating ATPases; D008274:Magnesium