Trypsin is a serine protease produced in the pancreas. Ethylenediaminetetraacetic acid (EDTA) is a chelating agent which sequesters metal ions such as Ca+2 and Mg+2,enhancing the trypsinization reaction. 0.05% Trypsin/EDTA solution (T/E) is a sterile, phosphate and HEPES-buffered saline solution with a pH of 7.4 at room temperature. It contains 0.05% trypsin and 0.5 mM EDTA.