MOPS

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The other mops

MOPS is the common name for the buffering compound in MOPS buffer. MOPS stands for 3-(N-morpholino) propanesulfonic acid and with a pKa of 7.20, MOPS is an good buffer for many biological systems at almost neutral pH. HEPES is a chemically similar pH buffering compound.

Recipe for 10x MOPS buffer

chemical structure of MOPS, 3-(N-morpholino) propanesulfonic acid
  • 41.2 g 3-(N-morpholino) propanesulfonic acid (MOPS)
  • 10.9 g Sodium Acetate, 3- hydrate
  • 3.7 g EDTA, sodium salt


  • add 800 ml of nuclease free distilled water; mix to dissolve
  • adjust to pH 7 with NaOH (prepared in nuclease free distilled water)
  • fill to the final volume of 1000 ml


  • filter sterilise or autoclave
  • store at room temperature
  • protect from light; do not use if the solution appears yellow

Final concentration of active compounds

  • 400 mM MOPS (buffering)
  • 100 mM NaAc
  • 10 mM EDTA (nuclease inhibition by Mg2+ chelation)

Stability of MOPS

Contrary to common belief, MOPS is sufficiently heat-stable to be autoclaved. This will not interfere with its buffering capacity. See, for example, Farrell RNA methods, p201 [1]


Some OWW protocols which use MOPS

External links