A Unique Ascorbate Peroxidase Active Component in the Cyanobacterium Synechococcus PCC 7942 (R2) |
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| Authors: | Anat Rozen Ron Mittler Yigal Burstein Elisha Tel-or |
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| Institution: |
a Department of Agricultural Botany, The Hebrew University of Jerusalem, Rehovot, Israel
b Department of Biochemistry, Cook College, Rutgers University, New Brunswick, NJ, USA
c Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel |
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| Abstract: | Ascorbate peroxidase active component (APAC) was purified and characterized in Synechococcus PCC 9742 (R2) cells. APAC was isolated from freshly harvested cells, by ion exchange chromatography on DEAE cellulose, ultrafiltration through a 3000 dalton cut off filter and high pressure liquid chromatography through a reversed phase C-18 column. APAC was found to be extremely stable to harsh treatments of boiling water for 30 min, acidification to pH 2.0 and proteolytic digestion. A close correlation between activity and iron content of APAC was observed throughout the purification steps. E.S.R. spectrum of APAC showed a resonance line at g = 4.3 in the oxidized from. Peroxide reduction by ascorbate decreased the E.S.R. signal, which reappeared upon reoxidation by H2O2. The affinities of APAC to H2O2 and ascorbate were high (0.38 mM and 0.2 mM, respectively). Amino acid composition analysis of APAC revealed the presence of glutamic acid: glycine: cysteine residues at 2: 1: 1 ratio. |
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| Keywords: | Ascorbate peroxidase hydrogen peroxide removal Fe-complex Synechococcus 7942 cyanobacteria |
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