Thermodynamic modeling of internal equilibria involved in the activation of trypsinogen

Massimo Coletta, Paolo Ascenzi, Laura Bravin, Gino Amiconi, Martino Bolognesi, Mario Guarneri, Enea Menegatti

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of activating dipeptides, sequentially homologous to the Ile 16-Vall 17 N-terminus of bovine β-trypsin (β-trypsin), on equilibria involved in the binding of strong ligands (i.e., n-butylamine, the bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor; BPTI) and the porcine pancreatic secretory trypsin inhibitor (Kazal-type inhibitor, type I; PSH)) to bovine trypsinogen (trypsinogen) was investigated at pH 5.5 (I = 0.1 M) and T = 21.0 ± 0.5°C; under the same experimental conditions, thermodynamics for the binding of strong ligands to β-trypsin was also obtained. The equilibria involved in the binding of activating dipeptides and/or inhibitors to β-trypsin and to its zymogen are described according to an induced-fit formalism, taking into account ligand-linked interactions) between different functional and structural domains of the (pro)enzyme possibly involved in the trypsinogen-to-β-trypsin activation pathway. The analysis of data is focussed on parameters describing interactions between the so-called Ile-Val pocket (where the Ilel6-Vall7 N-terminus of β-trypsin or activating dipeptides bind) and the primary and/or secondary recognition subsite(s) (where strong ligands associate) present in the (pro)enzyme. Such an analysis allows to dissect the contributions due to the primary recognition subsite, where small mono-functional ligands (e.g., n-butylamine) bind, from those of the secondary subsite(s), which are additional recognition clefts for macromolecular inhibitors (e.g., BPTI and PSTI).

Original languageEnglish
Pages (from-to)959-972
Number of pages14
JournalJournal of Biomolecular Structure and Dynamics
Volume7
Issue number4
DOIs
Publication statusPublished - 1990

Keywords

  • (β-)trypsin(ogen) inhibitors
  • Bovine trypsinogen
  • Bovine β-trypsin
  • Thermodynamic modeling of trypsinogen activation
  • Trypsinogen activating dipeptides
  • Trypsinogen activation

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

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