title: Asp41-His48 region of streptokinase is important in binding to a substrate plasminogen.
abstract: Streptokinase is a plasminogen activator protein produced by several strains of beta-hemolytic streptococci. Random mutagenesis of streptokinase was carried out for the determination of critical amino acid residues in plasminogen activation. We selected and sequenced 14 streptokinase mutants with no plasminogen activation activity on skim milk-plasminogen overlay plate. Specific activities of the selected streptokinase mutants were determined with chromogenic assay. Eight mutants (V19F, V35E, E85D, L292R, D325P, D341E, I345N, and M369L) resulted in greatly decreased amidolytic activities. However, unexpectedly, six mutants (D41C, S44K, S44P, R45P, H48T, and D220G) showed substantial amidolytic activities comparable to that of wild type. Moreover, five-point mutations were concentrated on the Asp41-His48 region. These data indicate that the Asp41-His48 region in a streptokinase-plasminogen binary complex plays an important role in binding to a substrate plasminogen.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Taejon, South Korea.
authors.forename: D M
authors.initials: DM
authors.lastname: Kim
authors.forename: S J
authors.initials: SJ
authors.lastname: Lee
authors.forename: I C
authors.initials: IC
authors.lastname: Kim
authors.forename: S T
authors.initials: ST
authors.lastname: Kim
authors.forename: S M
authors.initials: SM
authors.lastname: Byun
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002863:Chromogenic Compounds; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D010957:Plasmids; D010958:Plasminogen / Q000187:drug effects / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D013300:Streptokinase / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D002863:Chromogenic Compounds; D010958:Plasminogen; D013300:Streptokinase; D000581:Amidohydrolases