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Corpus Systématique Animale

Titre du document

Structural changes of alpha2- and ovomacroglobulins

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Springer (journals)
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Mots-clés d'auteur
  • alpha-2-macroglobulin
  • ovomacroglobulin
  • conformational change
  • electron microscopy
  • frictional ratio
  • proteinase inhibitor
Nom du fichier dans la ressource
  • Atsushi Ikai 1
  • Masaaki Nishigai 1
  • Toshiya Osada 1
  • Hideo Arakawa 1
  • Masako Kikuchi 1
  • 1) Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Tokyo, Japan

The plasma ?2-macroglobulin and its egg white homologue ovomacroglobulin were purified from several different species and their structure before and after the reaction with proteinases studied by electron microscopy. The negatively stained specimens showed either a ringlike structure or a flowerlike one before the reaction with proteinses, but their structures changed into open rectangular ones after the reaction. The translational frictional ratio f/f 0 of human ?2-macroglobulin and crocodilian ovomacroglobulin given in the literature is between 1.5 and 1.6 before and after the reaction with proteinases. The value reflects asymmetry due not to a high axial ratio, but rather to an openness of the structure resulting in a partially free draining character of the molecules. The computational method developed by Bloomfield and his co-workers based on the formalism of Kirkwood is used to calculate the frictional ratio of several models constructed from small spheres. The overall shape of the models is derived from electron micrographs. Although the degree of hydration is an unknown parameter in the calculation, reasonable agreement is obtained between the experimental values of f/f 0 and the calculated ones. Combination of electron microscopic and hydrodynamic methods would be fruitful in the structural study of giant proteins such as ?2-macroglobulin.

Catégories Science-Metrix
  • 1 - health sciences
  • 2 - biomedical research
  • 3 - biophysics
Catégories INIST
  • 1 - sciences appliquees, technologies et medecines
  • 2 - sciences biologiques et medicales
  • 3 - sciences biologiques fondamentales et appliquees. psychologie
Catégories Scopus
  • 1 - Life Sciences ; 2 - Biochemistry, Genetics and Molecular Biology ; 3 - Biochemistry
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Journal of Protein Chemistry

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