Proton coupling is preserved in membrane‐bound chloroplast ATPase activated by high concentrations of tentoxin

[摘要]

The effect of tentoxin at high concentrations was investigated in thylakoids and proteoliposomes containing bacteriorhodopsin and CF₀CF₁. Venturicidin-sensitive ATP hydrolysis, ATP-generated ΔpH and ATP synthesis were practically 100% inhibited at 2 μM tentoxin, and restored to various extents beyond 50 μM. With respect to the native enzyme, tentoxin-reactivated ATPase had the following properties: (i) a higher ΔpH requirement to synthetise ATP; (ii) a decreased futile proton flow through CF₀CF₁ (without ADP), which remains 100% blocked by ADP. It is concluded that despite its altered kinetic performances, tentoxin-modified CF₀CF₁ preserves its mechanism and remains a tightly coupled proton pump.

[学科分类] 生物化学/生物物理

[关键词] F0F1 H+-ATPase;Proton pump;Tentoxin;Inhibitor;Thylakoid;Proteoliposome;9-AA;9-aminoacridine;BR;bacteriorhodopsin;Chl;chlorophyll;transmembrane difference in proton electrochemical potential (electrochemical proton gradient);ΔpH;transmembrane pH difference;DTT;dithiothreitol;CF0CF1;chloroplast ATP synthase (H+-ATPase);(C)F0;membranous sector of the H+-ATPase;(C)F1;extrinsic;catalytic sector of the H+-ATPase;MES;2(N-morpholino)ethanesulfonic acid;PS1;photosystem 1;Tricine;N-[2-hydroxy-1;1-bis(hydroxymethyl)ethyl]glycine;TTX;tentoxin;VTCD;venturicidin;Enzyme;ATP synthase (EC 3.6.1.3)