A highly stable cambialistic-superoxide dismutase from Antrodia camphorata:: Expression in yeast and enzyme properties

A cDNA encoding a putative superoxide dismutase (SOD) was identified in expressed sequence tags of Antrodia camphorata, a medicinal mushroom found only in Taiwan. The deduced protein was aligned with Mn-SODs and Fe-SODs from other organisms, this SOD showed greater homology to Mn-SOD. Functional A. camphorata SOD protein was overexpressed in yeast and purified. The purified enzyme showed two active forms on a 12.5% native PAGE, a dimer and a monomer. The dimeric protein's half-life of deactivation at 80 degrees C was 7min, and its thermal inactivation rate constant K-d was 9.87 x 10(-2) min(-1). The enzyme was stable in a broad pH range from 5-11; in the presence of 0.4 M imidazole and 2% SDS. The atomic absorption spectrometric assay showed that 1.0 atom of manganese/iron (9: 1) was present in each SOD subunit. The high stability of the enzyme make it better suited than other cambialistic-SODs for use in cosmetics. The SOD also documents its future utility in developing anti-inflammatory agent and in the treatment of chronic diseases. (c) 2007 Elsevier B.V. All rights reserved.