MES hemisodium salt

MES hemisodium salt is a salt form of MES hydrate which in solution acts as a buffering agent used in biological and biochemical research. In addition, MES hydrate contains an ethanesulfonic moiety which consist of an OH group which readily loses a hydrogen atom to form the salt complex. MES hemisodium salt has a pK_a value of 6.15 and an optimum temperature of 20 degrees Celsius. Furthermore, MES hemisodium salt has minimal absorption in visible and UV radiation, is chemically and enzymatically stable, and does not change pK_a upon temperature change. MES is used as a running buffer for resolving very small proteins (ex: 13 kDa) on bis-tris gels. Also used in cation-exchange chromatography and as a biological buffer in plant cell cultures. MES solutions can be prepared to the desired pH by titrating the free acid with sodium hydroxide.