Digestive processes of haematophagous insects. XIII. Evidence for the digestive function of midgut proteinases of Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

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Abstract
Trysin (EC 3.4.21.4), proteinase VI, proteinase VII, aminopeptidase (EC 3.4.11.1), carboxypeptidase A (EC 3.4.12.2) and carboxypeptidase B (EC 3.4.11.3) occur in the posterior section of the midgut of unfed male and female G. m. morsitans and their activities rise after a blood meal. Only traces of these enzymes occur in the anterior midgut section. Elution profiles of proteins during Sephadex gel filtration of the anterior midgut at various times after feeding, and the low ratio of free amino acids to protein in the lumen of the anterior section of the midgut indicate that no significant hydrolysis of protein takes place there. Gel filtration results using material from the posterior section of the midgut indicate that proteins are rapidly converted to peptides and free amino acids, which occur in high concentration there. D gestion of proteins probably takes place only in the posterior section of the midgut; all 6 proteolytic enzymes may have digestive functions.