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      On the haemoprotein character of prostaglandin endoperoxide synthetase.

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          Abstract

          Prostaglandin endoperoxide synthetase is a membrane-bound glycoprotein isolated as a dimer of molecular weight of approximately 129 000 consisting of two identical polypeptide chains. Several research workers have reported that haemin (ferri-protoporphyrin-IX) is required to restore the full enzymic activity of the pure apoprotein. Difference spectroscopy shows association of haemin up to two molecules per polypeptide chain of molecular weight 70 000. Both the cyclooxygenase and the peroxidase activity displayed by the enzyme can be optimally stimulated by similar quantities of haemin. The restored haemin-enzyme complex has a millimolar absorption coefficient at 408 nm of 61 mM-1 . cm-1 per haem. Using this value, the presence of non-haem iron in the enzyme is virtually excluded. These findings and the spectra of the reassociated enzyme-haemin complex point to a haemoprotein character. The availability of haemin to the enzyme might play a regulating rôle in its action.

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          Author and article information

          Journal
          Biochim. Biophys. Acta
          Biochimica et biophysica acta
          0006-3002
          0006-3002
          Jan 29 1979
          : 572
          : 1
          Article
          0005-2760(79)90197-8
          104735
          5562f53a-b12a-4f1d-a043-3f81f86da0a2
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