Inhibition of serine proteinases by p-carbethoxyphenyl esters of εguanidino- and εamino caproic acid: Thermodynamic and molecular modeling study

Enea Menegatti, Mario Guarneri, Martino Bolognesi, Paolo Ascenzi, Gino Amiconi

Research output: Contribution to journalArticle

Abstract

The inhibitory effect of the clinically used p-carbethoxyphenyl ester of εguanidino-caproic acid metha-nesulphonate (εGCA-CEP) on the catalytic properties of human LYS77-plasmin (EC 3.4.21.7), bovine factor Xa (EC 3.4.21.6), bovine αthrombin (EC 3.4.21.5), ancrod (EC 3.4.21.28), crotalase (EC 3.4.21.30), bovine βtrypsin (EC 3.4.21.4), porcine pancreatic βkallikrein-B (EC 3.4.21.39, human urinary kallikrein (EC 3.4.21.35) and the Mr 54,000 species of human urokinase (EC 3.4.21.31) was investigated (between pH 2.0 and 8.5, I == 0.1 M;T == 21 ε 0.5εC), and analyzed in parallel with that of the homologous derivative p-carbethoxyphenyl εamino-caproate hydro chloride (εACA-CEP). On lowering the pH from 5.5 to 3.0, values of the apparent dissociation inhibition constant (Ki) for εGCA. CEP and εACA-CEP interaction with the serine proteinases considered increase, reflecting the acidic pK-shift upon inhibitor binding of a single ionizing group. Over the whole pH range explored, (i) εGCA-CEP interacts with bovine factor Xa and bovine αthrombin with an higher affinity than that observed for εACA-CEP binding; (ii) both inhibitors associate to bovine βtrypsin with the same affinity; and (iii) εACA-CEP inhibits human Lys77-plasmin and the Mr 54,000 species of human urokinase with an higher affinity than that reported for εGCA-CEP association, thus reflecting the known enzyme primary specificity properties. However, the affinity of εACA-CEP for ancrod, crotalase, porcine pancreatic βkallikrein-B and human urinary kallikrein, all of which preferably bind arginyl rather than lysyl side chains at the primary position of substrates and/or inhibitors, is paradoxically higher than that displayed by εGCA-CEP. By considering the amino acid sequences, the X-ray three-dimensional structures and/or the computer-generated molecular models of serine proteinase: inhibitor adducts, the observed binding behaviour of εGCA-CEP and εACA-CEP to the enzymes considered has been related to the inferred stereochemistry of proteinase: inhibitor contact region(s).

Original languageEnglish
Pages (from-to)249-259
Number of pages11
JournalJournal of Enzyme Inhibition and Medicinal Chemistry
Volume2
Issue number4
DOIs
Publication statusPublished - 1989

Keywords

  • Inhibitor adduct formation (thermodynamics of) serine proteinase
  • Inhibitor adducts (molecular modeling of)
  • Serine proteinase inhibitors. serine proteinase

ASJC Scopus subject areas

  • Drug Discovery
  • Pharmacology

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