Tentoxin has at least two binding sites on CF1 and ϵ‐depleted CF1 ATPases isolated from spinach chloroplast

[摘要]

A new procedure for synthesis of ¹⁴C-labeled tentoxin [¹⁴C-MePhe[(Z)Δ]³-tentoxin], with a high specific activity, is described. Binding experiments with CF₁ or CF₁-ϵ isolated from spinach chloroplast have been carried out using equilibrium dialysis technique. The results show the presence of two classes of binding sites. The association constants of the two major binding sites were derived from non-linear fitting of the binding curves. At 4°C, the first binding site has a value of K _a1 = 8.2 × 10⁵ M⁻¹ in CF₁ and 8.7 × 10⁵ M⁻¹ in CF₁-ϵ, while the second binding site has lower affinity with K _a2 = 1.5 × 10⁴ M⁻¹ in CF₁ and 2.3 × 10³ M⁻¹ in CF₁-ϵ.

[学科分类] 生物化学/生物物理

[关键词] H+-ATPase;Chloroplast ATP synthase;14C-Labelled tentoxin;Cyclic tetrapeptide;Equilibrium dialysis;Spinacia oleracea L.;CF0-F1;chloroplast ATP synthase (H+-ATPase);CF1;catalytic sector of the chloroplast H+-ATPase;CF1-ϵ;ϵ-subunit depleted CF1;Rt;retention time;s;singlet;d;doublet;t;triplet;m;multiplet;eq.;equivalent;K a;association constant;Enzyme;ATP synthase (EC 3.6.1.3.)