Reaction Captures Ephemeral Nitrosothiols

A method for capturing fleeting nitrosothiols may help biologists figure out how nitric oxide provokes a wide range of cellular processes, including cancer (J. Am. Chem. Soc., DOI: 10.1021/ja900370y). Nitrosothiols produced by the reaction of endogenous NO with the amino acid cysteine in proteins are thought to be a key mediator of NO's physiological effects, but little is known about how these transient chemical markers form or their ultimate fate. Ming Xian, Jiming Zhang, and Hua Wang of Washington State University, Pullman, capture unstable primary nitrosothiols (above, left) by reacting them with a phosphine thioester to give stable disulfides (above, right). Xian's group had previously shown that they could snag unstable tertiary nitrosothiols in this way. In the current study they show that the same mild reaction can tag more biologically relevant primary nitrosothiols, including S-nitrosoglutathione, a natural compound involved in NO signaling. Xian's team is now preparing biotin-linked, fluorescent-dye-linked, and solid-supported phosphine thioester reagents that can be used to detect S-nitrosolated proteins in biological samples.