Irreversible inactivation of glutathione peroxidase 1 and reversible inactivation of peroxiredoxin II by H2O2 in red blood cells.
Catalase, glutathione peroxidase1 (GPx1), and peroxiredoxin (Prx) II are the principal enzymes responsible for peroxide elimination in RBC. We have now evaluated the relative roles of these enzymes by studying inactivation of GPx1 and Prx II in human RBCs. Mass spectrometry revealed that treatment of GPx1 with H(2)O(2) converts the selenocysteine residue at its active site to dehydroalanine (DHA). We developed a blot method for detection of DHA-containing proteins, with which we observed that the amount of DHA-containing GPx1 increases with increasing RBC density, which is correlated with increasing RBC age. Given that the conversion of selenocysteine to DHA is irreversible, the content of DHA-GPx1 in each RBC likely reflects total oxidative stress experienced by the cell during its lifetime. Prx II is inactivated by occasional hyperoxidation of its catalytic cysteine to cysteine sulfinic acid during catalysis. We believe that the activity of sulfiredoxin in RBCs is sufficient to counteract the hyperoxidation of Prx II that occurs in the presence of the basal level of H(2)O(2) flux resulting from hemoglobin autoxidation. If the H(2)O(2) flux is increased above the basal level, however, the sulfinic Prx II begins to accumulate. In the presence of an increased H(2)O(2) flux, inhibition of catalase accelerated the accumulation of sulfinic Prx II, indicative of the protective role of catalase.
Cho
Chun-Seok
CS
Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul, Korea.
Lee
Sukmook
S
Lee
Geun Taek
GT
Woo
Hyun Ae
HA
Choi
Eui-Ju
EJ
Rhee
Sue Goo
SG
D000409:Alanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D020134:Catalytic Domain; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism; D054464:Peroxiredoxins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
C015102:dehydroalanine; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D005979:Glutathione Peroxidase; D050862:Oxidoreductases Acting on Sulfur Group Donors; C504024:SRXN1 protein, human; D000409:Alanine; D000094765:Glutathione Peroxidase GPX1; C000722067:GPX1 protein, human