Isolation and characterization of a trypsin-like enzyme from the buffalo fly, Haematobia irritans exigua

• Published in: Medical and veterinary entomology Vol. 9; no. 2; p. 120
• Main Authors: East, I J, Allingham, P G, Bunch, R J, Matheson, J
• Format: Journal Article
• Language: English
• Published: England 01-04-1995
• Subjects: Animals; Cattle; Endopeptidases - chemistry; Endopeptidases - isolation & purification; Hydrogen-Ion Concentration; Muscidae - enzymology; Muscidae - immunology; Sheep - immunology; Trypsin - chemistry; Trypsin Inhibitors - pharmacology; Vaccination
• ISSN: 0269-283X
• DOI: 10.1111/j.1365-2915.1995.tb00167.x

The incorporation of soybean trypsin inhibitor (SBTI) into the diet of the buffalo fly, Haematobia irritans exigua (De Meijere), results in increased mortality and reduced fecundity. A trypsin-like enzyme which binds to SBTI was isolated by affinity chromatography on a Sepharose-SBTI column followed by ion-exchange chromatography. The enzyme was inhibited by benzamidine, phenylmethylsulfonyl fluoride, ovomucoid, leupeptin and alpha-2 macroglobulin. The enzyme was not inhibited by EDTA or p-chloromecuribenzoic acid and had a broad pH optimum of pH 7-9. Vaccination of sheep produced antibodies specific for the trypsin-like enzyme which inhibited enzyme activity in vitro but did not affect the survival of flies maintained in in vitro culture.