Figure 2.

Effect of ATP and ADP on the conformational state of subunit ɛ, as monitored via fluorescence of Cy3 at 566 nm. Measurements were done at 59°C in buffer containing 100 mM KCl, 1 mM MgCl₂, 20 mM MES, 20 mM MOPS, 20 mM HEPES, 20 mM Tricine, 10% v/v glycerol, pH 7.9. Arrows indicate addition of nucleotides. Note the different timescales in panels A and B. Red traces: ATP added to 250 μM at time 0, no other additions. Purple traces: ATP added to 250 μM at time 0, ADP added later to 1 mM. Blue traces: ADP added to 1 mM at time 0, no other additions. Cyan traces: ADP added to 1 mM at time 0, ATP added later to 250 μM. (A) isolated F₁. (B) F₁ reconstituted with Bacillus PS3 inverted EDTA-treated membranes.