Cloning, expression and enzymatic characteristics of a 2-Cys peroxiredoxin from Antarctic sea-ice bacterium Psychrobacter sp. ANT206.

Peroxiredoxin (Prx, EC 1.11.1.15) is a family of the thiol-dependent antioxidant enzyme. In this study, a cold-adapted Prx gene from Antarctic psychrophilic bacterium Psychrobacter sp. ANT206 (PsPrx) consisted of an open reading frame (ORF) of 567 bp was cloned. Amino acid sequence analysis revealed that PsPrx contained one catalytic site (Thr45, Cys48 and Arg121) and could be categorized as a typical 2-Cys Prx. Compared with the mesophilic StPrx, PsPrx with a reduced amount of hydrogen bonds and salt bridges and other characteristics, may be responsible for its enzymatic stability and flexibility at low temperature. The recombinant PsPrx (rPsPrx) was purified to homogeneity by Ni-NTA and its enzymatic characterization was described. Interestingly, rPsPrx exhibited the maximum activity at 30 °C and remained 42.6% of its maximum activity at 0 °C. rPsPrx was a salt-tolerance enzyme that showed 42.2% of its maximum activity under 2.5 M NaCl. The kinetic parameters of different substrates revealed that it could efficiently catalyze the peroxides, especially H

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