Cloning and characterization of a thermostable superoxide dismutase from the thermophilic bacterium Rhodothermus sp. XMH10

Abstract

A superoxide dismutase (SOD) gene was cloned from the thermophilic bacterium Rhodothermus sp. XMH10 for the first time and highly expressed in Escherichia coli. The Rhodothermus sp. XMH10 SOD (RhSOD) gene encodes 209 amino acids with a putative molecular weight of 23.6 kDa and a pI value of 5.53. The recombinant RhSOD was detected to be an iron type SOD and existed as a dimer on its natural status. Experiments revealed that this RhSOD showed high activity at 50-70 degrees C and pH 5.0. Compared to SODs from other thermophiles, it was highly thermostable, maintaining more than 90% of its activity after incubation at 70 degrees C for 12 h, only totally inactivated after more than 4-h incubation at 80 degrees C. It also showed much higher resistance to KCN, NaN(3) and H(2)O(2) as compared to other SODs.

Cloning and Expression of One Chloroplastic Ascorbate Peroxidase Gene from Nelumbo nucifera

“…APX activity was estimated by measuring the amount of ascorbate (e 290 = 2.8 mM -1 cm -1 ), according to the method of Lu et al (2005). The effect of temperatures on APX activity was assayed according to the method of Wang et al (2008).…”

A novel, thermostable manganese-containing superoxide dismutase from Bacillus licheniformis

“…The enzyme activity corresponding to 100% was 9550 U mg -1 . Standard deviations of relative activities were in range of 1.5-3.4% (Wang et al 2008) and the SOD from thermophile Thermomyces lanuginosus with half-life 30 min at 70-75°C (Li et al 2005), the SOD from B. licheniformis M20 had exceptionally better thermal stability. The studied SOD from B. licheniformis M20, able to catalyze the conversion of superoxide ions or radicals under the moderate to high temperature environments is exceptionally useful in their removing or subtracting and has valuable potentials in different biotechnological processes.…”

“…In this connection, an increasing interest to the SODs from thermophiles and hyperthermophiles were observed (Wang et al 2008). Thermostable SODs have also a higher resistance to most chemical denaturants and could be very useful in the industries of pharmaceuticals, cosmetics, food, and biotechnology and in environmental protection.…”

Unique Characteristics of Recombinant Hybrid Manganese Superoxide Dismutase from Staphylococcus equorum and S. saprophyticus

“…Interestingly, few SODs can also be cambialistic, which means that the type of metal installed is exchangeable [20]. Further, SODs demonstrate stability against various environmental stress, particularly those originated from thermophilic or hyperthermophilic microorganisms [8][9][10][11][12][13][14]21]. Thermostable SOD are of interest for application such as sun cream and for its stability during production, formulation, shipping, and storage.…”

“…Many SODs are reported to display low activity at low pH [7][8][9][10][11][12][13][14] and to cope with that, strategies have been developed to improve the enzyme stability towards extreme pH condition. Immobilization the enzyme to nanoparticles appears as an attractive alternative because it prolongs and extends the use of the enzyme, as demonstrated in stabilization of SOD from Thermus thermophillus wl [15].…”