The differential specificity of chymotrypsin A and B is determined by amino acid 226

Péter Hudáky, Gyula Kaslik, István Venekei, László Gráf

Research output: Contribution to journalArticle

17 Citations (Scopus)


The A and B isoforms of the pancreatic serine proteinase, chymotrypsin are known to cleave substrates selectively at peptide bonds formed by some hydrophobic residues, like tryptophan, phenylalanine and tyrosine. We found, however, that the B forms of native bovine and recombinant rat chymotrypsins are two orders of magnitude less active on the tryptophanyl than on the phenylalanyl or tyrosyl substrates, while bovine chymotrypsin A cleaves all these substrates with comparable catalytic efficiency. Analysing the structure of substrate binding pocket of chymotrypsin A prompted us to perform an Ala226Gly substitution in rat chymotrypsin B. The specificity profile of the Ala226Gly rat chymotrypsin B became similar to that of bovine chymotrypsin A suggesting that only the amino acid at sequence position 226 is responsible for the differential specificities of chymotrypsin A and B isoenzymes.

Original languageEnglish
Pages (from-to)528-533
Number of pages6
JournalEuropean Journal of Biochemistry
Issue number1-2
Publication statusPublished - Jan 15 1999


  • Chymotrypsin B
  • Site specific mutagenesis
  • Specificity profile

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'The differential specificity of chymotrypsin A and B is determined by amino acid 226'. Together they form a unique fingerprint.

  • Cite this