Kinetic studies of the oxidation of glutathione in protein refolding buffer

Abstract

Here, we examined the change of glutathione (GSH) under different conditions and determined the appropriate kinetic schemes to describe its change of concentration. GSH was continuously oxidized into glutathione disulfide (GSSG) as incubation period increased at the temperatures ranging from 10 to 50 degrees Celsius while certain oxidation by-products were also observed at the later stage of reaction at higher temperatures (70-90 degrees Celsius). The addition of 0.3 mM GSSG in 3 mM GSH solution delayed the onset of GSH oxidation without significantly changing the rate of GSH oxidation. Our results also revealed that GSH oxidation could be facilitated upon the addition of copper (II) ion whereas GSH oxidation was found to be decelerated when EDTA was present. In kinetic analysis, the reaction orders of GSH oxidation under various conditions were determined. Moreover, the temperature dependence of the rate of GSH oxidation was modeled by Arrhenius and Eyring equations and resultant activation parameters were also presented.

Efficient Formation of N-(1-Deoxy-d-ribulos-1-yl)-Glutathione via Limited Oxidation and Degradation of Glutathione during the Atmospheric–Vacuum Thermal Reaction

“…28 The oxidation of cysteinyl in GSH was positively correlated with reaction time and reaction temperature. 24 At a molar ratio of 2:1, the yield of GSSG at 90 °C was higher than that at 80 °C during the 70 min reaction time (Figure 3b). GSSG as a diamine compound could react with Rib to produce the ARP of Rib-GSSG.…”

“…Due to the reactive sulfhydryl group, GSH was prone to undergo oxidation to produce the intermolecular coupling product GSSG during the preparation of RG-ARP (Figure a). ,, As shown in Figure d, the oxidation of GSH intensified with the increase in the reaction time, and the GSSG yield reached 8.46% after 30 min during the heat treatment, which was 1.65 times higher than the maximum yield of RG-ARP (5.12%) at the same reaction time. Thermal degradation was an important but not dominant consumption pathway of GSH during the thermal reaction (Figure a) .…”

“…1-DR was theoretically the predominating C 5 -α-dicarbonyl compound under an alkaline condition, but the reductone structure of 1-DR showed higher redox reactivity than that of 3-DR, resulting in the lower yields of 1-DR (Figure g,h) . The oxidation of cysteinyl in GSH was positively correlated with reaction time and reaction temperature . At a molar ratio of 2:1, the yield of GSSG at 90 °C was higher than that at 80 °C during the 70 min reaction time (Figure b).…”

“…Oxygen played an essential role in the conversion of reduced form GSH to oxidized form GSSG. 24 Due to the low oxygen content in vacuum dehydration, the yield of oxidation products increased slightly compared with that in atmospheric reaction. As shown in Figure 4c,d, the decrease of GSSG yield was accompanied by the increase of RGG-ARP yield at 60 °C with the prolongation of incubation time.…”

Studies of interaction between insulin and glutathione using electrospray ionization mass spectrometry

“…There is only the dissolved oxygen in the sample solution. It was reported that the air‐exposed sample solution can contain oxygen ~ 3.2 × 10 –4 mol/L at room temperature and 1 atm ambient pressure . The reaction products of insulin and GSH were less in sealed solution than those in air (shown in Fig.…”