preliminary characterization of digestive proteease in the mid-gut of the third larval instar of gasterophilus intestinalis

ABSTRACT

Protinases contained in the mid-gut of the early third instar of Gasterophilus intestinals have been tentatively identified by midgut hydrolysis of synthetic substrates. Trypsin was identified by maximal hydrolysis of benzoyl-DL-arginine-p-nitroanilide [BApNA] at pH 8 and chymotrypsin by maximal hydrolysis of benzoyl-L-tyrosine ethyl ester [BTEE] at pH 9. Carboxypeptidase A and B were identified by their maximal hydrolysis of hippuryl-DL-phenyllactic acid and hippuryl-L-arginine at pH 9 and 8 respectively. Aminopeptidase was identified by maximal hydrolysis of leucine-p-nitroanilide at pH 9. The mid-gut also showed activity of aspartic proteinase and identified it as cathepsin D.A drug [Banmith 12.5% pyrantel tartarate] used for the routine control of helminthes parasites of horses and donkies in Egypt was used in vitro to investigate its effect on the optimal activity of studied enzymes. It was found that the drug has no effect on trypsin and carboxypeptidase A while it decreases the activity of chymotrypsin, aminopeptidase and acidic proteinase and was also found to increase the activity of carboxypeptidase B greatly