Covalent binding of 1,N(6)-ethenoadenosine diphosphate to catalytic and noncatalytic sites of chloroplast ATP-synthase].

N P Tatarintsev, A N Mal'ian

Biofizika 2006 Mar-Apr

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The catalytic and noncatalytic sites of the chloroplast coupling factor (CF1) were selectively modified by incubation with the dialdehyde derivative of the fluorescent adenosine diphosphate analogue 1,N(6)-ethenoadenosine diphosphate. The modified CF1 was reconstituted with EDTA-treated chloroplast thylakoid membranes. The influence of light-induced transmembrane proton gradient and of phosphate ions on the fluorescence of 1,N(6)-ethenoadenosine diphosphate covalently bound to catalytic sites of reconstituted CF1 (ATP-synthase) was studied. Upon illumination of thylakoid membranes with saturating white light, the quenching of fluorescence of covalently bound 1,N(6)-ethenoadenosine diphosphate was observed. The quenching was reversed by the addition of inorganic phosphate to the reaction mixture in the dark. Repeated illumination induced the quenching once again: however, the addition of phosphate ions did not affect the fluorescence intensity now. When 1,N(6)-ethenoadenosine diphosphate was covalently bound to noncatalytic sites of ATP-synthase, no similar fluorescent changes were observed. The interrelation of the observed changes of 1,N(6)-ethenoadenosine diphosphate fluorescence and the mechanism of energy-dependent changes in the structure of the catalytic site of ATP-synthase is discussed.

Citation

N P Tatarintsev, A N Mal'ian. Covalent binding of 1,N(6)-ethenoadenosine diphosphate to catalytic and noncatalytic sites of chloroplast ATP-synthase]. Biofizika. 2006 Mar-Apr;51(2):282-7