| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Incubation of chloroplast thylakoids with pyridoxal 5'-phosphate for a short time (5s) modified the lysine residues of the beta subunit of ATP synthase. Except for lysine residues in the N-terminal and C-terminal regions, glycine-rich P-loop (GGAGVGK^<178>T), Lys154, and Lys167-containing peptide (P-peptide) exhibited especially high reactivity with pyridoxal 5'-phosphate. Energization of thylakoids or addition of substrates (ADP,Pi, ATP) affected the modifications of P-peptide, Lys447, and Lys399. P-peptide ; Substrates inhibited the modification. 0.5mM ADP inhibited it by 80%. Energization enhanced the inhibitory effects of substrates. Lys447 ; Substrates inhibited the modification. 0.5mM ADP inhibited it by 60%. Lys399 ; The reactivity depended on the transmembrane DELTAmu_<H+>. With increasing DELTAmu_<H+>, the reactivity decreased.
These results suggest the energy-dependent conformation changes at the catalytic nucleotide binding site and around Lys399. The former increases the affinity of the site for substrates. Substrate binding at the catalytic site changes the conformaiton around Lys447.
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