Effect of S-(1,2-Dicarboxyethyl) Glutathione andS-(1,2-Dicarboxyethyl) Cysteine on theStimulus-Induced Superoxide Generation andTyrosyl Phosphorylation of Proteins in HumanNeutrophils

We investigated the effects of S-(1,2-dicarboxyethyl) glutathione (DCEG) and S-(1,2-dicarboxyethyl) cysteine (DCEC) on the stimulus-induced superoxide generation and tyrosyl phosphorylation of proteins in human neutrophils. When the cells were preincubated with DCEG, the superoxide generation induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) was enhanced in concentration-dependent manner but DCEC showed no effect. The influence of DCEG and DCEC on phorbol 12-myristate 13-acetate-induced superoxide generation showed no effect. On the other hand, the superoxide generation induced by arachidonic acid was markedly suppressed by DCEG and DCEC in concentration-dependent manner. The suppression of DCEG was more effective than that of DCEC. The superoxide generation induced by fMLP in the DCEG-treated cells was suppressed by genistein. DCEG enhanced tyrosyl phosphorylation of 80.0 kDa, 60.0 kDa, and 45.0 kDa proteins in human neutrophils. The tyrosyl phosphorylation of 80.0 kDa, 60.0 kDa, and 45.0 kDa proteins was suppressed by genistein. The enhancement of tyrosyl phosphorylation of these proteins in the DCEG-treated cells was parallel to the enhancement of the fMLP-induced superoxide generation.