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. 2015 Mar 16;10(3):e0119874. doi: 10.1371/journal.pone.0119874

Fig 6. Role of Ca2+ binding to M4 in TNAP activity.

Fig 6

Dose-response of stimulation of AP activity (mean mA405nm/min) in steady-state (i.e. the slope measured between 60–90 min) at pH 9.8 (10 mM pNPP) for increasing [CaCl2], added to AbM2-bound Zn2+-TNAP and the indicated mutants, after pre-treatment with EDTA (2 h) and loading with 20 μM Zn2+; correlation between calculated apparent Kds for the functionally relevant Mg2+ and Ca2+ binding to TNAP and the three indicated TNAP mutants. Lines constructed in the absence and presence of 20 μM ZnCl2 are as indicated; Apparent Kds are represented with their respective SD.