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Isolation and functional characterization of the heavy and light chains of human tissue-type plasminogen activator

Author: Rijken, D.C. · Groeneveld, E.
Institution: TNO Gaubius Institute for Cardiovascular Research, 2313 AD Leiden, Netherlands
Source:Journal of Biological Chemistry, 7, 261, 3098-3102
Identifier: 230182
Keywords: Biology · Plasminogen activator · Human cell · Melanoma · Amino Acids · Binding Sites · Chromatography, Gel · Cyanogen Bromide · Electrophoresis, Polyacrylamide Gel · Fibrinogen · Fibrinolysis · Human · Iodoacetamide · Mercaptoethanol · Spectrophotometry · Support, Non-U.S. Gov't · Tissue Plasminogen Activator


Two-chain tissue-type plasminogen activator (t-PA), which consists of a heavy chain (M(r) ??? 38,000) and a light chain (M(r) ??? 31,000) connected by a disulfide bridge, was reduced with 2-mercaptoethanol and then air-reoxidized at a low protein concentration and carboxamidomethylated. The two chains were separated by means of zinc chelate-agarose, which was found to bind the light chain selectively. The light chain was fully active on the tripeptide substrate H-D-isoleucyl-L-prolyl-L-arginine p-nitroanilide (S-2288) and partially active on plasminogen. The plasminogen activator activity of the light chain was, in contrast to that of two-chain t-PA, not stimulated by fibrin or fibrinogen fragments. Fibrin-agarose chromatography of radiolabeled chains showed that only the heavy chain bound to fibrin. These results indicate that the active site-containing light chain in t-PA needs the heavy chain for fibrin stimulation of its plasminogen activator activity. Chemicals/CAS: plasminogen activator, 9039-53-6; Amino Acids; Cyanogen Bromide, 506-68-3; Fibrinogen, 9001-32-5; Iodoacetamide, 144-48-9; Mercaptoethanol, 60-24-2; Tissue Plasminogen Activator, EC