Improved stability and catalytic activity of chemically modified papain in aqueous organic solvents

András Szabó, Márta Kotormán, Ilona Laczkó, L. Mária Simon

Research output: Contribution to journalArticle

29 Citations (Scopus)


Papain was modified with the anhydrides of various monocarboxylic (acetic or propionic) and dicarboxylic (citraconic, maleic or succinic) acids. 7-10 of the 11 primary amino groups of the enzyme were modified. The organic solvent tolerances of the modified enzyme forms were increased (especially in the concentration range of 10-60%) in comparison with the unmodified enzyme. Acylation enhanced the catalytic activity and stability of papain both in buffer and in aqueous organic solvents (ethanol and acetonitrile). Decrease of the positive charges on the surface of papain resulted in a higher enzyme stability than when they were replaced by negative charges. The kinetic parameters revealed that in aqueous ethanol the maximum rates (Vmax) and Michaelis constants (KM) of the modified papain forms were increased, and higher catalytic efficiencies (kcat/KM) were detected as compared with the native enzyme. The results of near-UV circular dichroism and tryptophan fluorescence spectroscopic studies suggested that the modifications caused only local changes around the aromatic residues. The modified enzyme forms led to higher N-acetyl-l-tyrosine ethyl ester synthesis conversions in aqueous ethanol; acetyl and propionyl papain furnishing the highest productivity.

Original languageEnglish
Pages (from-to)199-204
Number of pages6
JournalProcess Biochemistry
Issue number2
Publication statusPublished - Feb 1 2009


  • Amino acid ester synthesis
  • CD and fluorescence spectroscopy
  • Chemical modification
  • Organic acid anhydrides
  • Organic solvents
  • Stability of papain

ASJC Scopus subject areas

  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology

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