MOPS
From OpenWetWare
Jump to navigationJump to search
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, makes a good buffering agent for many biological systems requiring neutral pH. HEPES is a chemically similar pH buffering compound.
Recipe for 10x MOPS buffer, 1 L
- 83.7 g MOPS; MW 209.3 g/mol
- 13.6 g Sodium Acetate, trihydrate; MW 136.1 g/mol (watch out: NaAc, anhydrous is only 82 g/mol or 8.2g)
- 3.7 g EDTA, disodium dihydrate; MW 372.24 g/mol (again check MW of the salt you stock)
- 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 is dark (yellow is ok)
Final concentration in 10x stock
- 400 mM MOPS (buffering)
- 100 mM NaAc
- 10 mM EDTA (nuclease inhibition by Mg2+ chelation)
Variation
Some protocols use a less concentrated MOPS buffer
- 200 mM MOPS - 41.9 g in 1 L
- 20 mM NaAc - 2.7 g
- 10 mM EDTA - 3.7 g
Stability of MOPS
Contrary to common belief, MOPS is sufficiently heat-stable to be autoclaved. Solution will turn yellow but this does not interfere with its buffering capacity. See, for example, Farrell RNA methods, p201 [2]. Straw coloured buffer is good but do not use darker buffer.
Some OWW protocols which use MOPS
- Jacobs:Protocol RNA Agarose Gel
- Knight:NuPAGE electrophoresis
- Sauer:bis-Tris SDS-PAGE, the very best
