MES (2-Morpholinoethanesulphonic acid) is a zwitterionic buffer effective in the pH range 5.5-7.0. As a Good's buffer, MES is extensively used to adjust pH in plant culture media, reagent solutions and physiological experiments.

Physicochemical Properties

Molecular Formula	C6H13NO4S
Molecular Weight	195.24
Exact Mass	195.056
CAS #	4432-31-9
Related CAS #	MES monohydrate;145224-94-8;MES sodium salt;71119-23-8;MES potassium;39946-25-3;MES-d13;352534-94-2
PubChem CID	78165
Appearance	White to off-white solid powder
Density	1.4±0.1 g/cm3
Melting Point	>300 °C(lit.)
Index of Refraction	1.517
LogP	-2.13
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	3
Heavy Atom Count	12
Complexity	214
Defined Atom Stereocenter Count	0
InChi Key	SXGZJKUKBWWHRA-UHFFFAOYSA-N
InChi Code	InChI=1S/C6H13NO4S/c8-12(9,10)6-3-7-1-4-11-5-2-7/h1-6H2,(H,8,9,10)
Chemical Name	2-morpholin-4-ylethanesulfonic acid
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

References	[1]. Hydrogen ion buffers for biological research. Biochemistry. 1966 Feb;5(2):467-77. [2]. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex. Front Plant Sci. 2016 Feb 18;7:79.
Additional Infomation	2-(N-morpholino)ethanesulfonic acid is a Good's buffer substance, pKa = 6.15 at 20 ℃. It is an organosulfonic acid and a MES. It is a conjugate acid of a 2-(N-morpholino)ethanesulfonate. It is a tautomer of a 2-(N-morpholiniumyl)ethanesulfonate.

Solubility Data

Solubility (In Vitro)	H2O: 125 mg/mL (640.24 mM) DMSO: 50 mg/mL (256.10 mM)
Solubility (In Vivo)	Solubility in Formulation 1: 50 mg/mL (256.10 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	5.1219 mL	25.6095 mL	51.2190 mL
	5 mM	1.0244 mL	5.1219 mL	10.2438 mL
	10 mM	0.5122 mL	2.5610 mL	5.1219 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.