EGTA

EGTA is the chemical name for Ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid, a synthetic chelating agent used to bind calcium ions (Ca2+). It is a polyamino carboxylate that exhibits a high affinity for Ca2+ and, relative to many other divalent cations, strong selectivity for calcium over magnesium (Mg2+). In aqueous solutions, EGTA forms a complex with Ca2+, effectively reducing free calcium ion concentration. The calcium-binding affinity of EGTA is pH-dependent, increasing with higher pH; optimal binding occurs under mildly basic conditions (approximately pH 7.2–8.0). Commercial preparations are available mainly as the disodium salt (Na2EGTA), which is water-soluble, as well as in the free-acid form.

EGTA is widely used in biology and biochemistry to control intracellular and extracellular calcium levels. It functions as a calcium buffer in solutions, enabling researchers to clamp or titrate free Ca2+ concentrations in experiments. This capability is important for studying calcium-dependent processes such as enzyme activity, muscle contraction, neurotransmitter release, and various signaling pathways. In electrophysiology and cell biology, EGTA is often employed to inhibit calcium-triggered events, either alone or in combination with other buffers to set precise free Ca2+ levels (the CaEGTA buffering system).

Availability and handling: EGTA is routinely sold as a laboratory reagent, stored as a dry powder or in buffered solutions. It should be handled with standard chemical-safety practices, and solutions should be prepared at the appropriate pH to achieve the desired calcium-binding properties.