title: Direct kinetics of bait region cleavage of alpha-2-macroglobulin by a rapid quenching method.
abstract: The rate of bait region cleavage of human alpha-2-macroglobulin by chymotrypsin was determined by a rapid quenching method under conditions where the bimolecular encounter between the two reactants was not rate-limiting. alpha 2M was first mixed with a 30 molar excess of chymotrypsin in a sequential stopped-flow apparatus and after programmed time intervals the activity of chymotrypsin was quenched with 1 N HCl. The fraction of uncleaved subunits was quantitated by SDS-PAGE under reducing conditions. The result indicated that the bait region cleavage proceeded following a two-exponential decay curve with respective rate constants of k1 = 40 s-1 and k2 = 2 s-1.
authors.affiliation: Laboratory of Biodynamics, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Shibuya
authors.forename: A
authors.initials: A
authors.lastname: Ikai
mesh_terms: D001665:Binding Sites; D002918:Chymotrypsin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006851:Hydrochloric Acid; D007700:Kinetics; D008297:Male; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D000511:alpha-Macroglobulins; D002918:Chymotrypsin; D006851:Hydrochloric Acid