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The Enzymatic Degradation of Hemoglobin, especially Studies on Heme α-Methenyl Oxygenase NAKAJIMA HIROSHI 1,2 1First Department of Internal Medicine, Faculty of Medicine, Kyushu University 2Department of Clinical Genetics, Tokyo Medical and Dental University pp.31-41
Published Date 1962/2/15
DOI https://doi.org/10.11477/mf.2425906219
  • Abstract
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 A new enzyme, heme α-methenyl oxygenase, which catalizes the transformation of pyridine-hemichromogen as well as hemoglobin-haptoglobin to a direct precursor of biliverdin, is demonstrated in beef and guinea-pig liver and characterized.

 1) The enzyme activity is present predominantly in the liver and kidney, and is practically absent from the reticuloendotherial system such as spleen and bone marrow.

 2) The enzyme is shown to be distributed in the supernatant fraction of beef liver obtained by the cell fractionation technic.

 3) The enzyme was purified from an ace-tone powder of beef liver as a starting material through three steps of purification. The most purified enzyme preparation seemed to catalize all the steps in this process.

 4) The enzyme protein, in a crude or purified state, was remarkably sensitive to atomospheric oxygen.

 5) The enzyme required both TPNH and ferrous iron as its cofactors.

 6) The reaction was inhibited by the addition of metal chelating agents as well as sulfhydryl inhibitors, but not by catalase.

 7) The final reaction product was isolated as crystalline form. It is similar but not identical to verdohemochrome described by Lemberg following pyridine-hemichromogen's chemical degradation using ascorbic acid and oxygen.

 8) The product dissolved in chloroform has shown four absorption bands in the visible spectrum at 397mμ, 495mμ, 530mμ, and 657 mμ.

 9) The product forms a 2,4-dinitrophenyl-hydrazone and exhibits a positive Schiff's reaction and several other aldehyde reactions.

 10) The crystalline product is easily convertible into biliverdin with the concomitant liberation of iron and formaldehyde.

 11) In reference to the substrate specificity, hemoglobin-haptoglobin complex rather than free hemoglobin was found to be the reactive substrate in this enzyme system. The possible mechanism of hemoglobin degradation in vivo was also discussed.


Copyright © 1962, THE ICHIRO KANEHARA FOUNDATION. All rights reserved.

基本情報

電子版ISSN 1883-5503 印刷版ISSN 0370-9531 金原一郎記念医学医療振興財団

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