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    • Keywords


      Oxyhaemoglobin; deoxyhaemoglobin; methaemoglobin; ligand; superoxide; superoxide dismutase; erythrocyte

    • Abstract


      Superoxide is continuously generated in the erythrocytes, and oxyhaemoglobin from different animals including fish, amphibians, reptiles, birds, flying mammals, mammals and human beings acts as a scavenger of superoxide. The approximate rate constants of the reaction between superoxide and oxyhaemoglobin of different animals are 0.32-1.6 × 107M-1 s-1. Results obtained with anion ligands like CN- and N3- indicate that superoxide preferentially reacts with anion ligand-bound deoxyhaemoglobin. Carbonmonoxyhaemoglobin and methaemoglobin are ineffective. Work with photochemically generated oxyradical indicate that oxyhaemoglobin may also act as a scavenger of singlet oxygen. The rate constant of the reaction between superoxide and human oxyhaemoglobin is Kapp= 6.5×106 M-1 s-1, which is about three orders less than Ksod(2× 109 M-1 s-1). Thus, in the erythrocytes, oxyhaemoglobin would appear to act as a second line of defence. Oxyhaemoglobin appears to be as effective as superoxide dismutase for scavenging superoxide in the erythrocytes.

    • Author Affiliations


      Asoke Mal1 Anuradha Nandi1 I B Chatterjee1

      1. Department of Biochemistry, University College of Science, 35, Ballygunge Circular Road, Calcutta - 700 019, India
    • Dates

  • Journal of Biosciences | News

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      Posted on July 25, 2019

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