Fig. 9.

(A) Representative srtA melting curves in the presence of different CaCl₂ concentrations. At higher calcium concentrations, the srtA protein is stabilized towards higher melting points. (B) Determination of the thermodynamic dissociation constant K_D for the srtA-Ca²⁺ complex from the melting point vs. CaCl₂-concentration relationship by regression with a binding isotherm ${\mathrm{T}}_{\mathrm{m}}\left(\mathrm{c}\right)={\mathrm{T}}_{\mathrm{m}}\left(\mathrm{m}\mathrm{i}\mathrm{n}\right)+({\mathrm{T}}_{\mathrm{m}}\left(\mathrm{m}\mathrm{a}\mathrm{x}\right)-{\mathrm{T}}_{\mathrm{m}}\left(\mathrm{m}\mathrm{i}\mathrm{n}\right))\bullet (1-{\mathrm{e}}^{-\mathrm{k}\bullet \mathrm{c}})$ with ${\mathrm{K}}_{\mathrm{D}}=\frac{\mathrm{l}\mathrm{n}(2)}{\mathrm{k}}$ . Shown are means ± standard deviation (n = 3).