Electron microscope studies of human alpha 2-macroglobulin-chymotrypsin complex: demonstration that the two structures assigned to native and proteolyzed alpha 2-macroglobulin represent two views of the proteolyzed molecule

Biochemical and Biophysical Research Communications
J K StoopsD K Strickland


Electron microscope studies of native and protease-bound human alpha 2-macroglobulin have led to two contradictory models for these two structures. One viewpoint maintains that the native structure has the shape of )+(, which contracts on binding of the protease to the shape of ([). An opposing view proposes that the native structure has the shape of a padlock and that )+( and ([) are the side and end views of the proteolyzed molecule. In this investigation, electron microscope studies of the alpha-chymotrypsin-treated alpha 2-macroglobulin utilizing a tilt stage have shown that the two shapes [)+( and ([)] interconvert. This demonstrates that these two shapes represent the side and end views of the proteolyzed alpha 2-macroglobulin which are related by a 90 degree rotation of the prototype molecule.


Sep 1, 1985·Proceedings of the National Academy of Sciences of the United States of America·S R FeldmanS V Pizzo
Mar 1, 1988·Proceedings of the National Academy of Sciences of the United States of America·J P BretaudiereJ K Stoops
Mar 23, 1973·Biochimica Et Biophysica Acta·Y Jacquot-Armand, G Krebs
Apr 1, 1968·The Journal of Experimental Medicine·B BlothS E Svehag
Mar 1, 1972·The Biochemical Journal·J M JonesR A Kekwick


Jan 1, 1992·Electron Microscopy Reviews·E DelainF Van Leuven
Jul 15, 1992·Proceedings of the National Academy of Sciences of the United States of America·J K StoopsS J Wakil

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