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. Author manuscript; available in PMC: 2010 Mar 13.
Published in final edited form as: J Mol Biol. 2009 Mar 13;386(5):1265–1277. doi: 10.1016/j.jmb.2009.01.022

Figure 5.

Figure 5

Pentamidine (Pnt) binding to Ca2+-S100A1. Displacement of TAMRA-labeled TRTK12 bound to Ca2+-S100A1 by the FDA approved drug pentamidine as monitored by a decrease in TAMRA-TRTK12 fluorescence anisotropy. The sample conditions included 3.5 μM S100A1, 50 nM TAMRA-labeled TRTK12, 25 mM NaCl, 1.0 mM CaCl2, 1 mM DTT, 5 mM HEPES buffer, pH 7.5, at 25 °C. The PntKD calculated from this competition experiment (PntKD=120 ± 60 μM) relied on the dissociation of TAMRA-labeled TRTK12 from Ca2+-S100A1 (TAMRA-TRTKKD = 1.0 ± 0.6 μM; inset). In this titration (inset), S100A1 was titrated into a solution where [TAMRA-TRTK] was kept constant (50 nM) with all other buffer conditions the same as in the competition experiment.