GLYOXALASE

Abstract

Reduced glutathione was first shown by Lohmann (1) to be a specific activator of the enzyme glyoxalase, which converts methylglyoxal into lactic acid.The amount of activation was dependent, within a certain range, upon the concentration of glutathione.On the basis of this relationship a new manometric method for the estimation of glutathione has been developed.The amount of glutathione may be determined from the amount of activation it produces with a given quantity of enzyme.It was apparent from the work of Lohmann on muscle and liver glyoxalase, and of Platt and Schroeder (2) on acetone-yeast glyoxalase, that greater changes in activity were produced by increasing amounts of glutathione where low concentrations of the latter were used.At higher concentrations the activity approached a maximum beyond which further increases in glutathione gave no increased activity.Therefore, to use the activity produced as a measure of the glutathione present, it is essential to work in the range of low concentrations.The extreme specificity of glutathione for this reaction was pointed out by Lohmann.Only the reduced form has any effect.Oxidized glutathione, cysteine, thioglycolic acid, hydrogen sulfide, hydrogen cyanide, pyrophosphate, citrate, and hydroxyquinoline had no activating effect whatsoever.To this list thioneine and ascorbic acid, two substances which are known to react in iodometric methods, are now added.Thus this specificity provides US with a means of distinguishing glutathione, particularly in tissues, from other sulfhydryl compounds and ascorbic acid.1