Fig. 4.
Effect of pH on heme binding to apo-LmCld. (A) shows 3 μM holo-LmCld at different pH values; conditions: 50 mM citrate/phosphate buffer, pH 4.0–7.0; 50 mM phosphate buffer, pH 6.5–8.0; 50 mM glycine buffer, pH 7.5–10.0. The inset depicts the pH dependence of the Reinheitszahl (RZ) of holo-LmCld; black dots are in absence of and gray triangles in presence of 150 mM NaCl. In (B)–(D) 4 μM holo LmCld were present in 5 mM phosphate buffer pH 7.0 and diluted rapidly using stopped-flow technique with 100 mM citrate/phosphate buffer, pH 4.0 (B), 100 mM phosphate buffer, pH 7.0 (C), and 100 mM glycine buffer, pH 10.0 (D). The starting spectra are depicted in black, spectra after 1 ms in cyan and resulting spectra in red, intermediate spectra are represented in gray. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)