Hemoglobin glutathionylation can occur through cysteine sulfenic acid intermediate: Electrospray ionization LTQ-Orbitrap hybrid mass spectrometry studies

Quantitation of protein S-glutathionylation by liquid chromatography–tandem mass spectrometry: Correction for contaminating glutathione and glutathione disulfide

“…Although endogenous thiols were detected, disulfide exchange with endogenous thiols is not a factor affecting PSSG content during this experiment. This supports observations by Regazzoni and coworkers indicating that disulfide exchange can occur only at GSSG concentrations that exceed physiological relevance [44]. Similarly, no singly labeled GSSG was detected, suggesting that autoxidation was not appreciable during tissue processing.…”

“…They interpreted the observation as a marker for ''slight oxidative'' stress and noted that fluctuations in GSSG and PSSG can occur with no effect on the bulk pool of free GSH. A potential mechanistic explanation of this relationship involves a central role of hydrogen peroxide that can induce sulfenic acid formation [44] and subsequent formation of PSSG, as well as through glutathione peroxidase-mediated metabolism, resulting in GSSG formation [49]. Further study is necessary to determine whether glutathionylation is an indiscriminate protective process or a more targeted phenomenon, as might be inferred by the recent observation in Salmonella typhimurium where posttranslational modification occurred more often on buried thiol residues than on those nearer the surface [50].…”

HPLC analysis of human erythrocytic glutathione forms using OPA and N-acetyl-cysteine ethyl ester: Evidence for nitrite-induced GSH oxidation to GSSG

“…Nevertheless, our findings suggest considerable formation of HbSSG in lysed RBC incubated with nitrite and hydrogen peroxide. The recent findings by Aldini et al [33] are supportive of the results of the present study.…”

“…10 suggest that the clear decrease of tGSH caused by H 2 O 2 is associated with formation of glutathione mixed disulfides with hemoglobin and other RBC proteins which are not present in the UF analyzed. These findings are supported by a recent study by Aldini et al who showed abundant formation of S-glutathionylated hemoglobin in similar experiments [33].…”

“…Also, it has been reported that methemoglobin is reduced back to hemoglobin, with GSH being oxidized to GSSG [26]. Formation of mixed disulfides of GSH with proteins including hemoglobin (HbSSG) has been observed by other investigators [33,37,38]. Measurement of HbSSG should be possible with the method reported here, for instance by adding NACET to the protein fraction of lysed RBC, subsequent ultrafiltration, and HPLC analysis of the UF, but measurement of HbSSG was beyond the aim of the present study.…”