Isolation, characterization and biological activity of a diuretic myokinin neuropeptide from the housefly, Musca domestica

摘要: Abstract A competitive ELISA employing a polyclonal antiserum raised against leucokinin-I was used to isolate and purify myokinin (muscakinin) from 1.05 kg of adult houseflies ( Musca domestica ). Following solid-phase purification, seven HPLC column steps were 4.8 nmol leucokinin-immunoreactive material. Sequence analysis mass spectrometry consistent with the structure Asn-Thr-Val-Val-Leu-Gly Lys-Lys-Gln-Arg-Phe-His-Ser-Trp-Gly NH 2 . This peptide synthesized co-eluted natural on three different columns. The activities synthetic muscakinin identical, both producing 4–5 fold increase in fluid secretion by housefly Malpighian tubules at nanomolar concentrations. presence pair basic residues (Lys-Lys) suggested might be processed further, pGlu-Arg-Phe-His-Ser-Trp-Gly being produced conversion an N-terminal glutamine pyroglutamic acid. However, this analog 1000-fold less active than intact peptide, comparable activity AK-V which shares same C-terminal pentapeptide sequence. diuretic is more double that previously identified CRF-related -DP) housefly, two peptides act synergistically stimulating secretion. Muscakinin also increased frequency amplitude contractions hindgut further contribute excretory process.