Purification and partial characterization of feline pepsinogen.
OBJECTIVE
To purify and partially characterize feline pepsinogen (fPG) from the gastric mucosa and compare fPG with PGs of other species.


METHODS
Stomachs of 6 cats.


METHODS
A crude protein extract was prepared from the gastric mucosa of feline stomachs. Feline PG A was purified by ammonium sulfate precipitation, weak-anion-exchange chromatography, size-exclusion chromatography, and strong-anion exchange chromatography. Partial characterization consisted of estimation of molecular weights (MWs) and isoelectric points, N-terminal amino acid sequencing, and investigation of susceptibility to pepstatin inhibition.


RESULTS
Several fPG A-group isoforms were identified. The MWs of the isoforms ranged from 37,000 to 44,820. Isoelectric points were all < pH 3.0. The proteolytic activity of the activated PGs was inhibited completely by pepstatin in a range of equimolar to 10-fold molar excess. The specific absorbance of fPG A was 1.29. The N-terminal amino acid sequence of the first 25 residues of the predominant fPG A7 had 75%, 72%, 64%, and 56% homology with PG A of dogs, rabbits, cattle, and humans, respectively. Sequences of 4 other fPG A-group isoforms were similar to fPG A7. All isoforms were immunologically cross-reactive with sheep anti-fPG A7 antiserum.


CONCLUSIONS
PG A is the only identified type of PG in cats and, similar to pg in other species, comprises multiple isoforms. The availability of fPG A may be used to facilitate the development of an immunoassay to quantify serum fPG A as a potential marker for gastric disorders in cats.
Gastrointestinal Laboratory, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4474, USA.
Ursula
U
Tress
Jörg M
JM
Steiner
Craig G
CG
Ruaux
Jan S
JS
Suchodolski
David A
DA
Williams
D000595:Amino Acid Sequence; D000818:Animals; D002415:Cats / Q000378:metabolism*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005753:Gastric Mucosa / Q000737:chemistry*; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009943:Organophosphorus Compounds; D020116:Pepsinogen A / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification*; D010436:Pepstatins / Q000378:metabolism; D020033:Protein Isoforms; D020539:Sequence Analysis, Protein; D013045:Species Specificity
C043517:2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide; D009943:Organophosphorus Compounds; D010436:Pepstatins; D020033:Protein Isoforms; D020116:Pepsinogen A; C031375:pepstatin