Functional Analysis of Recombinant Pancreatic Secretory Trypsin Inhibitor Protein With Amino-Acid Substitution

J Gastroenterol. 2002;37(11):928-34. doi: 10.1007/s005350200156.


Background: We hypothesized that mutation of the pancreatic secretory trypsin inhibitor ( PSTI) gene may promote a predisposition to pancreatitis, possibly by reducing the inhibition of trypsin activity. Based on this hypothesis, we performed a biochemical analysis of recombinant PSTI protein.

Methods: The trypsin inhibitory activity of the recombinant protein was analyzed. The activity of PSTI protein with a point mutation of the most common type: (34)Asn (AAT)-to-Ser (AGT)(101A>G N34S: N34S) in exon 3, was compared with that of the wild type.

Results: The function of N34S PSTI remained unchanged under both the usual alkaline and acidic conditions compared with the wild-type PSTI. The calcium concentration did not affect the activity of recombinant PSTI. The trypsin susceptibility of the N34S protein was not increased either.

Conclusions: Mechanisms other than the conformational change of PSTI associated with amino-acid substitution, such as abnormal splicing, may underlie the predisposition to pancreatitis in patients with the N34S mutation.

MeSH terms

  • Amino Acid Substitution / genetics*
  • Animals
  • Carrier Proteins
  • Cattle
  • Disease Models, Animal
  • Gene Expression / genetics
  • Genetic Predisposition to Disease
  • Growth Substances / genetics*
  • Humans
  • In Vitro Techniques
  • Intercellular Signaling Peptides and Proteins / genetics*
  • Mutagenesis, Site-Directed / genetics
  • Mutation / genetics*
  • Pancreatitis / genetics*
  • Recombinant Proteins / genetics*
  • Time Factors
  • Trypsin Inhibitor, Kazal Pancreatic / genetics*


  • Carrier Proteins
  • Growth Substances
  • Intercellular Signaling Peptides and Proteins
  • Recombinant Proteins
  • SPINK1 protein, human
  • Trypsin Inhibitor, Kazal Pancreatic