ß-N-acetylhexosaminidases in the secretion of the female reproductive accessory glands of Ceratitis capitata (Diptera)

The analysis by isoelectric focusing of the secretion fluid (AGF) of the female accessory glands of Ceratitis capitata has shown the presence of seven major protein fractions and two β-N-acetylhexosaminidase isoenzymes, HEX 1 and HEX 2, focalizing at pH 4.75 and 5.25, respectively. The two isoenzymes have the same molecular weight (69 kDa) but a different hydrolytic activity against and galactopyranoside, and a pH optimum of 4 at 37°C. AGF β-N-acetylhexosaminidase activity is most stable at pH values between 5 and 8. At neutral pH a rapid loss of activity is observed at temperatures higher than 50°C. Preliminary assays, carried out using chitin as substrate, indicate the presence in the secretion of an endochitinase activity not bound to the β-N-acetylhexosaminidase isoenzymes. The enzymatic modifications of specific lectin binding sites on the surface of gametic cells is most probably one of the necessary steps preceding fertilization.