Properties of glutathione insulin transhydrogenase from beef liver.

The glutathione-insulin transhydrogenase from beef liver haa been found to promote the reductive cleavage of the disulfide bonds of insulin by simple sulfhydryl compounds such as glutathione (2). The properties of this enzyme are of interest not only because of its probable involvement in the biological regulation of the level of insulin but also because, at present, it is the only isolated mammalian enzyme that can catalyze the reductive cleavage of a protein. The present paper describes some of the properties of the beef liver glutathione-insulin transhydrogenase.