A new method of isolation and some properties of the heavy chain of human plasmin.
A method is described by which the heavy chain of human plasmin, obtained by partial reduction of urokinase-activated plasminogen with 2-mercaptoethanol, is adsorbed on lysine coupled to polyacrylamide. The heavy chain is recovered from the adsorbent by elution with 6-aminohexanoic acid (yield 60-65%). Sulfhydryl titrations of the heavy chain showed that the partial reduction involved primarily the cleavage of the sole interchain disulfide bridge of plasmin. Dodecylsulfate-polyacrylamide electrophoresis gave essentially a single band corresponding to a component of about 60000 molecular weight. The NH2-terminal amino acid was predominantly threonine. 6-Aminohexanoic acid at different concentrations caused significant variations of the sedimentation and diffusion constants of the heavy chain indicating inhibitor-induced conformational alterations of the protein. The present results suggest that in plasmin only the heavy chain is capable of interacting with 6-aminohexanoic acid, and it appears that it is primarily this chain which plays an important role in the inhibition of the enzyme by 6-aminohexanoic acid.
D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005341:Fibrinolysin / Q000302:isolation & purification; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D010958:Plasminogen / Q000378:metabolism; D011485:Protein Binding; D013438:Sulfhydryl Compounds / Q000032:analysis; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D000596:Amino Acids; D046911:Macromolecular Substances; D013438:Sulfhydryl Compounds; D010958:Plasminogen; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator