Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology vol:132 issue:1 pages:27-35
Angiotensin converting enzyme (ACE) activity, defined as a captopril-inhibitable dipeptidyl carboxypeptidase activity towards H-3-hippurylglycylglycine, was demonstrated in haemolymph, testes and ovaries of the grey fleshfly Neobellieria bullata, hereby suggesting a physiological role for ACE in these particular tissues. While the ACE activity in haemolymph and testes reached relatively high levels, only minute ACE activity could be detected in ovaries throughout the entire vitellogenic cycle. Ovarian extracts of Neobellieria bullata do contain, however, in addition to Neb-TMOF, the Neobellieria bullata trypsin modulating oostatic factor which is an in vitro and a putative in vivo substrate of ACE in circulation, several other heat-stable molecules which individually function either as an ACE substrate or ACE inhibitor. Presumably these ACE interactive factors mask ACE activity in the fly ovaries, as measured by a classic substrate-binding assay. Purification and characterisation of these ACE substrate s/inhibitors is in progress and is likely to facilitate the elucidation of the enigmatic physiological relevance of ACE in insects. (C) 2002 Elsevier Science Inc. All rights reserved.