In vitro degradation of the Neb-Trypsin Modulating Oostatic Factor (Neb-TMOF) in gut luminal content and hemolymph of the grey fleshfly, Neobellieriabullata

The unblocked hexapeptidic Trypsin Modulating Oostatic Factor of the fleshf ly, an inhibitor of both trypsin and ecdysone biosynthesis, resists very we ll proteolytic breakdown by enzymes present in the lumen of the gut of prev itellogenic fleshflies. However, when incubated in hemolymph of adult flies , females and males, its half-life time is a mere 0.5 min. In hemolymph of last instar larvae, this value increases to about 1.5 min. Whereas PMSF, a potent inhibitor of serine proteases has no effect, captopril and lisinopri l, both known to be specific inhibitors of mammalian angiotensin I converti ng enzyme (ACE), effectively inhibit TMOF breakdown in fly hemolymph. Diges tion of Neb-TMOF by recombinant Drosophila AnCE on itself results in identi cal degradation products as with total hemolymph. In both cases ESI-Qq-oa-T of mass spectrometry demonstrated the appearance of peptide fragments with the sequences HPTN, LH and NP. These observations not only confirm the repo rted presence of circulating ACE-like activity in flies but also strongly s uggest that in flies this hemolymph ACE-like activity might be involved in the regulation of the oostatic activity as exerted by Neb-TMOF. (C) 2001 El sevier Science Ltd. All rights reserved.