Metabolism of Manduca sexta allatostatin by hemolymph of larvae of the tomato moth, Lacanobia oleracea

Abstract

The degradation of synthetic Manduca sexta allatostatin (Manse-AS) by hemolymph from larvae of the tomato moth, Lacanobia oleracea was investigated using reversed phase-high performance liquid chromatography (RP-HPLC), and matrix assisted laser desorption ionisation-time of flight mass spectrometry. Metabolism of 1 nmole Manse-AS in diluted hemolymph was rapid, t 1/2 = 3.5 min, with a number of products produced. Mass spectrometry of HPLC fractions identified cleavage products, which indicated a sequential degradation of Manse-AS from the N-terminal to Manse-AS (7–15). The most abundant products identified were Manse-AS (5–15), (6–15), and (7–15). These metabolites were synthesized and assayed for biological activity on juvenile hormone (JH) biosynthesis in vitro. All three of the above deletion peptides showed allatostatin activity, but were not as potent as Manse-AS (1–15).