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Substrate specificity of tissue-type and urokinase-type plasminogen activators

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Author: Rijken, D.C. · Groeneveld, E.
Type:article
Date:1991
Institution: Gaubius Instituut TNO
Source:Biochemical and Biophysical Research Communications, 2, 174, 432-438
Identifier: 231514
Keywords: Biology · Amino Acid Sequence · Binding Sites · Cells, Cultured · Enzyme Precursors · Human · Hydrogen-Ion Concentration · Kidney · Kinetics · Melanoma · Molecular Sequence Data · Plasminogen Activators · Substrate Specificity · Support, Non-U.S. Gov't · Tissue Plasminogen Activator · Tumor Cells, Cultured · Urinary Plasminogen Activator

Abstract

Recent studies suggest that plasminogen activators not only hydrolyse a specific arginine-valine bond in plasminogen, but may also cleave other proteins such as fibronectin. We studied the substrate specificity, particularly the preference for arginyl over lysyl peptide bonds, of tissue-type plasminogen activator (t-PA) as well as of two-chain urokinase-type plasminogen activator (u-PA). The arginine/lysine preference was determined with three pairs of tripeptidyl-p-nitroanilide substrates having either arginine or lysine in the P1 position and varied from 5.2 to 14.1 for u-PA and from 55.6 to 99.8 for t-PA. It was concluded that both t-PA and u-PA preferred arginyl to lysyl peptide bonds. However, u-PA had a significantly lower arginine/lysine preference than t-PA, indicating that u-PA represents a less specific proteinase. This may point to functions of u-PA other than plasminogen activation, which involve cleavage of lysyl bonds.