Purification and characterization of a psychrophilic glutathione reductase from Antarctic ice microalgae Chlamydomonas sp. strain ICE-L. Polar Biol

ArticleinPolar Biology 31(1):23-30 · November 2007with9 Reads
Impact Factor: 1.59 · DOI: 10.1007/s00300-007-0328-5

    Abstract

    A psychrophilic glutathione reductase from Antarctic ice microalgae Chlamydomonas sp. Strain ICE-L was purified by ammonium sulfate fractionation and three steps of chromatography. The yield was up to 25.1%
    of total glutathione reductase in the crude enzyme extract. The glutathione reductase activity was characterized by the spectrophotometric
    method under different conditions. Purified glutathione reductase was separated by SDS-PAGE, which furnished a homogeneous
    band. The native molecular mass of the enzyme was 115 kDa. Apparent Km values for NADPH and NADH (both at 0.5 mmol L−1 oxidized glutathione) were 22.3 and 83.8 μmol L−1, respectively. It was optimally active at pH 7.5, and it was stable from pH 5 to 9. Its optimum temperature was 25�C, with
    activity at 0�C 23.5% of the maximum. Its optimum ion strength and optimum Mg2+ were 50–90 and 7.5 mmol L−1, respectively. Ca2+, Mg2+, and cysteine substantially increased the activity of the enzyme but chelating agents, heavy metals (Cd2+, Pb2+, Cu2+, Zn2+, etc.), NADPH, and ADP had significant inhibitory effects. This glutathione reductase can be used to study the adaptation
    and mechanism of catalysis of psychrophilic enzymes, and it has a high potential as an environmental biochemical indicator
    under extreme conditions.