Ethylene glycol bis(2-aminoethylether)-N, N, N', N'-tetra acetic acid (EGTA) is a unspecific protease inhibitor like EDTA, but with a high selectivity for Ca2+ over Mg2+. Inhibition results from chelating of metal ions leading to their removal from the surrounding medium. An excess of Ca2+ or Mg2+ compensates the inhibitory effect of EGTA. Ethylene glycol bis(2-aminoethylether)-N, N, N', N'-tetra acetic acid (EGTA) is a unspecific protease inhibitor like EDTA, but with a high selectivity for Ca2+ over Mg2+. Inhibition results from chelating of metal ions leading to their removal from the surrounding medium. An excess of Ca2+ or Mg2+ compensates the inhibitory effect of EGTA.