title: Covalent and non-covalent interaction of chymotrypsin with alpha 2-macroglobulin.
abstract: The pattern of covalent crosslinking between human alpha 2-macroglobulin (alpha 2M) and chymotrypsin has been investigated by chromatography and polyacrylamide gel electrophoresis in denaturing medium. Reaction with a single mol of chymotrypsin per mol alpha 2M results in the formation of a 95% covalent 1:1 chymotrypsin-alpha 2M complex and in the proteolytic cleavage of both 180 kDa monomers in one alpha 2M subunit. Proteolytic cleavage in the other alpha 2M subunit requires the presence of a second mol of chymotrypsin; part (20%) of the protease in the 2:1 chymotrypsin-alpha 2M complex thus formed appears to be non-covalently bound to the alpha 2M chains. Covalent binding is abolished when the reaction of alpha 2M with the protease is carried out in the presence of hydroxylamine. A single mol of the protease is then able to cleave all four 180 kDa monomers in alpha 2M.
mesh_terms: D001665:Binding Sites; D002918:Chymotrypsin / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D011485:Protein Binding; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D000511:alpha-Macroglobulins; D002918:Chymotrypsin