title: Structure and function of microplasminogen: reconstitution of microplasminogen and microplasmin from isolated fragments.
abstract: We describe limited chemical proteolysis of microplasminogen/microplasmin (mPlg/mPlm) and their reconstitution from isolated fragments. A V141-->M141 substitution in methionineless human mPlg/mPlm allowed the protein(s) to be cleaved in CNBr/formic acid. The resulting two fragments (141 and 118 residues, respectively), each internally disulfide bonded, were separated by preparative non-reducing gradient SDS-PAGE, and could then be mixed to reconstitute the characteristic mPlg/mPlm, including their activation by urokinase (uPA) and streptokinase (SK), and inhibition by macromolecular inhibitors. The isolated larger, N-terminal fragment, which contains the mPlg activation site in a normal disulfide configuration, was not cleaved by uPA in the absence of its smaller C-terminal companion, showing that the linear amino acid sequence is not by itself sufficient to confer substrate character, even when its conformation is constrained by the disulfide structure.
authors.affiliation: Department of Pharmacological Sciences, State University of New York at Stony Brook 11794-8651, USA.
authors.forename: T
authors.initials: T
authors.lastname: de los Santos
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: E
authors.initials: E
authors.lastname: Reich
mesh_terms: D000595:Amino Acid Sequence; D004355:Drug Stability; D005341:Fibrinolysin / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D010958:Plasminogen / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D013329:Structure-Activity Relationship
chemical_list: D010446:Peptide Fragments; C111879:microplasminogen protein, human; C054561:microplasmin; D010958:Plasminogen; D005341:Fibrinolysin