PBS-EDTA Solution, Calcium and Magnesium Free

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• Trypsin-EDTATrypsin-EDTA is a cell dissociation reagent that combines the serine protease trypsin, which cleaves peptide bonds on the C-terminal side of lysine and arginine residues in cell-surface and matrix proteins, with the chelator EDTA, which binds the calcium and magnesium ions that cell-adhesion molecules require. It is supplied in a calcium- and magnesium-free balanced salt solution, most commonly at 0.05% trypsin (0.5 g/L) for routine cell lines and 0.25% (2.5 g/L) for firmly adherent cells and primary cultures. Typical use is 2-5 minutes at 37 degrees C, followed immediately by neutralisation with serum-containing medium or a defined trypsin inhibitor.
• PBS vs DPBS: What Is Different, and Which One to UsePBS and DPBS are both phosphate-buffered saline solutions; the difference is the recipe, not the function. Dulbecco's formulation (DPBS) adds potassium chloride and carries roughly twice the phosphate of a typical PBS (about 9.5 mM versus about 4 mM), and it is sold in two versions - with calcium and magnesium, and without. In practice the with-or-without-divalent-cations choice matters far more than the PBS-or-DPBS label: use a calcium- and magnesium-free solution to wash cells before trypsinisation or EDTA dissociation, because Ca2+ and Mg2+ support the cadherin and integrin bonds you are about to break, and use the version containing calcium and magnesium when cells must stay attached and intact through the wash.