BAPTA is a membrane-impermeable calcium chelator that binds extracellular calcium ions.1,2 The presence of four carboxylic acid functional groups allows for the binding of two calcium ions. BAPTA and its derivatives are widely used for the measurement and manipulation of intracellular free calcium concentration.
1.Sabnis, R.W.Handbook of biological dyes and stains: Synthesis and industrial applications(2010) 2.Grynkiewicz, G., Poenie, M., and Tsien, R.Y.A new generation of Ca2+ indicators with greatly improved fluorescence propertiesJ. Biol. Chem.260(6)3440-3450(1985)