The superoxide dismutase (SOD, EC 1.15.1.1) of Deinococcus radiophilus, a bacterium extraordinarily resistant to UV, ionizing radiations, and oxidative stress, was purified 1,920-fold with a 58% recovery yield from the cell-free extract of stationary cells by steps of ammonium sulfate fractionation and Superdex G-75 gel-filtration chromatography. A specific activity of the purified enzyme preparation was ca. 31,300 U mg(-1) protein. D. radiophilus SOD is Mn/FeSOD, judging by metal analysis and its insensitivity to cyanide and a partial sensitivity to H2O2. The molecular weights of the purified enzyme estimated by gel chromatography and polyacrylamide gel electrophoresis are 51.5+/-1 and 47.1+/-5 kDa, respectively. The SOD seems to be a homodimeric protein with a molecular mass of 26 +/- 0.5 kDa per monomer. The purified native SOD showed very acidic pI of ca. 3.8. The enzyme was stable at pH 5.0-11.0, but quite unstable below pH 5.0. SOD was thermostable up to 40 degrees C, but a linear reduction in activity above 50 degrees C. Inhibition of the purified SOD activity by beta-naphthoquinone-4-sulfonic acid, rho-diazobenzene sulfonic acid, and iodine suggests that lysine, histidine, and tyrosine residues are important for the enzyme activity. The N-terminal peptide sequence of D. radiophilus Mn/FeSOD (MAFELPQLPYAYDALEPHIDA(> D) is strikingly similar to those of D. radiodurans MnSOD and Aerobacter aerogenes FeSOD.

We report here a case with hypereosinophilia and peripheral artery occlusion. A 32-yr-old Korean woman presented to us with lower extremity swelling and pain. Angiography revealed that multiple lower extremity arteries were occlusive. The biopsy specimen showed perivascular and periadnexal dense eosinophilic infiltration in dermis and subcutaneous adipose tissue. Laboratory investigations revealed a persistent hypereosinophilia. She was prescribed prednisolone 60 mg daily. Her skin lesion and pain were improved and the eosinophil count was dramatically decreased. After discharge, eosinophil count gradually increased again. Cyanosis and pain of her fingers recurred. She had been treated with cyclophosphamide pulse therapy. Her eosinophilia was decreased, but the cyanosis and tingling sense were progressive. The extremity arterial stenoses were slightly progressed. Skin biopsy showed perivascular eosinophilic infiltration in the dermis and CD40 ligand (CD40L) positive eosinophilic infiltration. The serum TNF-α was markedly increased. These results suggest that CD40L (a member of TNF-α superfamily) could play a role in the inflammatory processes when eosinophil infiltration and activation are observed. We prescribed prednisolone, cyclophosphamide, clopidogrel, cilostazol, beraprost and nifedipine, and she was discharged.

The production of superoxide dismutase (SOD) varied in Deinococcus radiophilus, the UV resistant bacterium, depending upon different phases of growth, UV irradiation, and superoxide treatment. A gradual increase in total SOD activity occurred up to the stationary phases. The electrophoretic resolution of the SOD in cell extracts of D. radiophilus at each growth phase revealed the occurrence of MnSOD throughout the growth phases. The SOD profiles of D. radiophilus at the exponential phase received oxidative stress by the potassium superoxide treatment or UV irradiation also revealed the occurrence of a single SOD. However, these treatments caused an increase in SOD activity. The data strongly suggest that D. radiophilus has only one species of SOD as a constitutive enzyme, which seems to be a membrane-associated protein.

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