title: Functional analysis of recombinant pancreatic secretory trypsin inhibitor protein with amino-acid substitution.
abstract: 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.
authors.affiliation: Department of Surgery II, Kumamoto University Medical School, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Kinuko
authors.initials: K
authors.lastname: Kuwata
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirota
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimizu
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakae
authors.forename: Shoji
authors.initials: S
authors.lastname: Nishihara
authors.forename: Akio
authors.initials: A
authors.lastname: Takimoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Mitsushima
authors.forename: Norihisa
authors.initials: N
authors.lastname: Kikuchi
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Endo
authors.forename: Masayasu
authors.initials: M
authors.lastname: Inoue
authors.forename: Michio
authors.initials: M
authors.lastname: Ogawa
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D002352:Carrier Proteins; D002417:Cattle; D004195:Disease Models, Animal; D015870:Gene Expression / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006133:Growth Substances / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D010195:Pancreatitis / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics*; D013997:Time Factors; D014359:Trypsin Inhibitor, Kazal Pancreatic / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; C486642:SPINK1 protein, human; D014359:Trypsin Inhibitor, Kazal Pancreatic