BIOCHEMICAL-EVIDENCE OF ANGIOTENSIN II-LIKE PEPTIDES AND PROTEINS IN THE BRAIN OF THE RHYNCHOBDELLID LEECH THEROMYZON TESSULATUM

The peptides contained in neurons localized in the brain of the leech Theromyzon tessulatum (Hirudinae, Rhynchobdellida) and showing an immu nopositive reaction with an antibody directed against angiotensin II(A II), were purified by reversed-phase HPLC. Three AII-like peptides (P1 , P2 and P3) which exhibited the same retention times and chromatograp hic behaviors as synthetic AVII (fragment 6-8 of AII), AIV (fragment 3 -8 of AII) and AII, respectively, were resolved in brain extracts. An identification of the proteins immunoreactive to an anti-AII was perfo rmed at the level of both brain extracts and in vitro brain-translated RNA products. The protein detected at the level of the brain extracts (of a molecular mass of similar to 18 kDa) is multipeptidic as it is also recognized by two other antisera, a polyclonal one directed again st gamma-MSH and a monoclonal one (Tt159) raised against a leech brain epitope. It could be the pro-AII-like precursor. The protein detected at the level of in vitro brain-translated RNA products (of a molecula r mass of similar to 19 kDa) could be the prepro-AII-like precursor.