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Iron-Dependent Superoxide Dismutase from Novel Thermoacidophilic Crenarchaeon Acidilobus saccharovorans: from Gene to Active Enzyme

E. S. Slutskaya1*, E. Yu. Bezsudnova1, A. V. Mardanov2, I. V. Safenkova1, S. Yu. Kleimenov3, N. A. Chebotareva1, V. M. Gumerov2, N. V. Ravin2, K. G. Skryabin2,4, and V. O. Popov1,4

1Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33, 119071 Moscow, Russia; fax: (495) 954-2804; E-mail: elslutskaya@yandex.ru

2Bioengineering Center, Russian Academy of Sciences, pr. 60 Let Oktyabrya 7/1, 117312 Moscow, Russia

3Koltzov Institute of Development Biology, Russian Academy of Sciences, ul. Vavilova 26, 119334 Moscow, Russia

4Russian National Research Center “Kurchatov Institute”, pl. Akademika Kurchatova 1, 123182 Moscow, Russia

* To whom correspondence should be addressed.

Received May 14, 2012; Revision received July 5, 2012
A gene encoding superoxide dismutase was revealed in the genome of the thermoacidophilic crenarchaeon Acidilobus saccharovorans. A recombinant expression vector was constructed and transformed into E. coli cells. The novel recombinant superoxide dismutase was purified and characterized. The enzyme was shown to be an iron-dependent superoxide dismutase able to bind various bivalent metals in the active site. According to differential scanning calorimetric data, the denaturation temperature of the enzyme is 107.3οC. The maximal activity of the Fe(II) reconstituted enzyme defined by xanthine oxidase assay is 1700 U/mg protein. Study of the thermal stability of the superoxide dismutase samples with various metal contents by tryptophan fluorescence indicated that the thermal stability and activity of the enzyme directly depend on the nature of the reconstituted metal and the degree of saturation of binding sites.
KEY WORDS: Acidilobus saccharovorans, metalloenzyme, Fe-dependent superoxide dismutase, thermal stability

DOI: 10.1134/S0006297912120048