Figure 1.

WGp31-GroEL binding monitored by tryptophan fluorescence. (A–D) Each protein pair was incubated at 25°C for 2 min prior to the addition of Mg²⁺ and K⁺. After an additional 30 sec, the protein interaction was triggered by the addition of 1 mM ATP. After 2 min, a 7.5-fold excess of His-GroES was added as competitor. All experiments were performed in 100 mM Tris-HCl (pH 7.5), 2 mM DTT, 5 mM MgCl₂, 5 mM KCl with 2 μM GroEL, 2 μM WGp31, and 15 μM His-GroES proteins (protomer concentrations).