Haemophilus influenzae 티올 과산화효소의 특성

Characterization of Haemophilus influenzae Thiol Peroxidase

Haemophilus influenzae HI0571 protein that shows homology to E. coli thiol peroxidase uses yeast thioredoxin system as an electron donor[Hwang. Y. S., Chae. H. Z., and Kim. K. (2000) J. Biochem. Mol. Biol. 33, 514~518]. The microorganism has two open, reading frames. HI1158 and HI0084, showing homology to a thioredoxin reductase and a thioredoxin, respectively. Both proteins consisting thioredoxin system were expressed in E. coli, and then the proteins were subsequently purified. The H. influenzae thioredoxin system showed 5.5’-dithiobis-(2-nitrobenzoic acid) reduction activity. H, influenzae HI0751 protein, thiol peroxidase was characterized using the thioredoxin system as an electron donor. The thiol peroxidase showed the thioredoxin dependent peroxidase activity. And glutamine synthetase protection activity of thiol peroxidase against Thiol/Fe³⁺/O₂ system was enhanced by addition of the thioredoxin. An antioxidant function of thiol peroxidase in intact cells was demonstrated by the observation that E. coli cells overexpressed with H. influenzae thiol peroxidase were less sensitive to growth inhibition by alkyl hydroperoxides.