Choosing a Biological Buffer: Tris, HEPES and MES Compared
How the buffer you pick changes enzyme activity, metal-ion availability and assay reproducibility — and how to choose deliberately.
Start from pH, not from habit
Buffering capacity is only reliable within about one pH unit of the pKa. Tris sits near 8.1, HEPES near 7.5 and MES near 6.1 — so the working pH of your assay should select the buffer, not the other way round.
Temperature and interference
Tris has a comparatively large temperature coefficient, so its pH shifts as the assay warms. HEPES has a low temperature coefficient and is preferred for cell work, though it can participate in radical chemistry. MES binds metal ions only weakly, which makes it the better choice where a metal cofactor is essential.
Practical selection map
Nucleic-acid and protein purification: Tris. Cell culture and most enzymology near physiological pH: HEPES. Low-pH enzymology and carbodiimide conjugation: MES. Choosing the wrong buffer typically shows up as unexplained loss of activity rather than an obvious failure.
Related materials
TRIS Base and TRIS-HCl, High-Purity Biological Buffer →HEPES, High-Purity Biological Buffer →MES Monohydrate, High-Purity Biological Buffer →Request a Quote or Sample
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