ABSTRACT
There is now a very substantial body of evidence showing that glutathione (GSH) plays a key role in protecting cells against oxidative challenge and toxic substances. 1 , 2 Until recently it was widely considered that glutathione is ubiquitous among living organisms and essential for life. However, most of the data on glutathione metabolism has come from animal studies and much less is known about glutathione in plants, fungi, and microorganisms. In 1978 we reported the results of an initial survey of GSH in bacteria which indicated that many species of bacteria, including both aerobes and anaerobes, do not make glutathione. 3 The bacteria did contain other nonprotein thiols but these could not be identified at the time. Since there must have been extensive diversification among prokaryotes prior to the evolution of the cyanobacteria and the subsequent accumulation of oxygen in the atmosphere, a study of the thiols produced by widely divergent bacterial species promised to provide insights into the factors which led to GSH playing such a dominant role in eukaryotes. In the past decade we have developed methods based upon fluorescent labeling of thiols followed by separation using high-performance liquid chromatography (HPLC) which permits the specific determination of a wide range of thiols of biological interest, including GSH. 4 These have been used to survey the thiols produced by a broad selection of prokaryotes. 5 , 6 We summarize here the results of these studies, including results not previously published, and attempt to assess their implications for the evolution and function of glutathione.
