title: Converting tissue plasminogen activator to a zymogen: a regulatory triad of Asp-His-Ser.
abstract: Unlike most serine proteases of the chymotrypsin family, tissue-type plasminogen activator (tPA) is secreted from cells as an active, single-chain enzyme with a catalytic efficiency only slightly lower than that of the proteolytically cleaved form. A zymogenic mutant of tPA has been engineered that displays a reduction in catalytic efficiency by a factor of 141 in the single-chain form while retaining full activity in the cleaved form. The residues introduced in the mutant, serine 292 and histidine 305, are proposed to form a hydrogen-bonded network with aspartate 477, similar to the aspartate 194-histidine 40-serine 32 network found to stabilize the zymogen chymotrypsinogen.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
authors.forename: E L
authors.initials: EL
authors.lastname: Madison
authors.forename: A
authors.initials: A
authors.lastname: Kobe
authors.forename: M J
authors.initials: MJ
authors.lastname: Gething
authors.forename: J F
authors.initials: JF
authors.lastname: Sambrook
authors.forename: E J
authors.initials: EJ
authors.lastname: Goldsmith
mesh_terms: D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry; D001483:Base Sequence; D002384:Catalysis; D002918:Chymotrypsin / Q000737:chemistry / Q000378:metabolism; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010958:Plasminogen / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D010959:Tissue Plasminogen Activator / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D004792:Enzyme Precursors; D017395:Plasminogen Activator Inhibitor 1; D001224:Aspartic Acid; D012694:Serine; D006639:Histidine; D010958:Plasminogen; D002918:Chymotrypsin; D010959:Tissue Plasminogen Activator