Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Structural changes of alpha2- and ovomacroglobulins


The plasma α2-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 α2-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 α2-macroglobulin.

This is a preview of subscription content, log in to check access.


  1. Barrett A., and Starkey P. M. (1973). Biochem. J. 133, 709–724.

  2. Bloth B., Chesebro B., and Svehag S.-E. (1968). J. Exp. Med. 127, 749–756.

  3. Branegard B., Osterberg R., and Sjoberg B. (1982). Eur. J. Biochem. 122, 633–666.

  4. Debanne M. T., Bell R., and Dolovich J. (1975). Biochim. Biophys. Acta. 411, 295–304.

  5. Donovan J. W., Mapes C. J., Davis J. G., and Hamburg R. D. (1969). Biochemistry 8, 4190–4199.

  6. Feinman, R. E. (ed.). (1983). Chemistry and Biology of Alpha-2-Macroglobulin. 421, 1–478.

  7. Garcia Bernal J. M., and Garcia de la Torre J. (1981). Biopolymers 20, 129–139.

  8. Garcia de la Torre J., and Bloomfield V. A. (1981). Q. Rev. Biophys. 14, 81–139.

  9. Gonias S. L., Reynolds J. A., and Pizzo S. (1982). Biochim. Biophys. Acta 705, 306–314.

  10. Hall P. K., and Roberts R. C. (1978). Biochem. J. 171, 27–38.

  11. Hanover J. A., Rudick J. E., Willingham M. C., and Pastan I. (1983). Arch. Biophys. Biochem. 227, 570–579.

  12. Ikai A., Kitamoto T., and Nishigai M. (1983). J. Biochem. 93, 121–127.

  13. Kitamoto T., Nakashima M., and Ikai A. (1982). J. Biochem. 92, 1679–1682.

  14. Kurecki T., Kress L. F., and Laskowski Sr. M. (1979). Anal. Biochem. 99, 415–420.

  15. Miller H. T., and Feeney R. E. (1966). Biochemistry 5, 952–958.

  16. Nagase H., HarrisJr. E. D., Woessner J. F., and Brew K. (1983). J. Biol. Chem. 258, 7481–7489.

  17. Nishigai M., Osada T., and Ikai A. (1985). Biochim. Biophys. Acta 831, 236–241.

  18. Ohlsson K. (1971). Acta Physiol. Scand. 81, 269–272.

  19. Osterberg R., and Malmensten B. (1984). Eur. J. Biochem. 143, 541–544.

  20. Pochon F., Amand B., and Lavalette D. (1978). J. Biol. Chem. 253, 7496–7499.

  21. Schramm H., and Schramm W. (1982). Hoppe-Seyler's Physiol. Chem. 363, 803–812.

  22. Sottrup-Jensen L., Petersen T. E., and Magnusson S. (1980). FEBS Lett. 121, 275–279.

  23. Sottrup-Jensen L., Stepanik T. M., Kristensen T., Wierzbicki D. M., Jones C. M., Lonblad P. B., Magnusson S., and Petersen T. E. (1984). J. Biol. Chem. 259, 8318–8327.

  24. Starkey P. M., and Barrett A. J. (1977). In Proteinases in Mammalian Cells and Tissues (Barrett A. J., ed.), Elsevier/North-Holland Biomedical Press, Amsterdam.

  25. Tapon-Bretaudiere J., Bros A., Couture-Tosi E., and Delain E. (1985). EMBO J. 4, 85–89.

  26. Weber K., and Osborn M. (1969). J. Biol. Chem. 244, 4406–4412.

Download references

Author information

Additional information

This article was presented during the proceedings of the International Conference on Macromolecular Structure and Function, held at the National Defence Medical College, Tokorozawa, Japan, December 1985.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Ikai, A., Nishigai, M., Osada, T. et al. Structural changes of alpha2- and ovomacroglobulins. J Protein Chem 6, 81–93 (1987).

Download citation

Key words

  • alpha-2-macroglobulin
  • ovomacroglobulin
  • conformational change
  • electron microscopy
  • frictional ratio
  • proteinase inhibitor