1. Converting tissue plasminogen activator to a zymogen: a regulatory triad of Asp-His-Ser.
- Author
-
Madison EL, Kobe A, Gething MJ, Sambrook JF, and Goldsmith EJ
- Subjects
- Amino Acid Sequence, Aspartic Acid chemistry, Base Sequence, Catalysis, Chymotrypsin chemistry, Chymotrypsin metabolism, Enzyme Precursors chemistry, Histidine chemistry, Hydrogen Bonding, Kinetics, Molecular Sequence Data, Mutagenesis, Site-Directed, Mutation, Plasminogen metabolism, Plasminogen Activator Inhibitor 1 metabolism, Serine chemistry, Tissue Plasminogen Activator chemistry, Tissue Plasminogen Activator genetics, Enzyme Precursors metabolism, Tissue Plasminogen Activator metabolism
- 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.
- Published
- 1993
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