Oxidation of 2-mercaptoethanol in the presence of tris buffer

Abstract

2-Mercaptoethanol is oxidized by molecular oxygen, especially at high pH. This reaction is markedly increased by primary amines such as asparagine, glutamine and their corresponding amino acids and by the buffer tris(hydroxymethyl)aminomethane. Thus, the use of 2-mercaptoethanol in Tris buffer may present several complications: an uptake of oxygen which could be confused with metabolic activity; destruction of the protective mercaptoethanol; and by inference, quite possibly an enhanced oxidation of the protein sulphydryls in need of protection.