Identification of a new tachykinin from the midgut of the desert locust, Schistocerca gregaria, by ESI-Qq-oa-TOF mass spectrometry

This paper reports the purification of a tachykinin isoform from the midgut of the desert locust, Schistocerca gregaria. One hundred locust midguts we re extracted in an acidified methanolic solvent, after which three HPLC col umn systems were used to obtain a pure peptide. A tachykinin immunoassay wa s used to monitor all collected fractions. After each purification step the purity of the sample was monitored by MALDI-TOF mass spectrometry. The pur e peptide was sequenced by ESI-Qq-oa-TOF mass spectrometry. Ed-man degradat ion-based automated microsequencing and chemical synthesis confirmed the se quences. The midgut peptide, GNTKKAVPGFYGTRamide (Scg-midgut-TK), belongs t o the tachykinin family with identified members in all vertebrate phyla and some invertebrate phyla: arthropods, annelids and molluscs. Scg-midgut-TK is the first tachykinin purified from midguts of the desert locust Schistoc erca gregaria. In comparison to locust brain tachykinins, the midgut tachyk inin is N-terminally extended. Similar to neuropeptide gamma, an N-terminal ly extended mammalian tachykinin, first isolated from rabbit intestine, the present identified locust intestinal tachykinin contains a putative dibasi c cleavage site. (C) 1999 Academic Press.