Isolation and characterization of schistostatin-2(11-18) from the desert locust, Schistocerca gregaria: a truncated analog of schistostatin-2.
An octapeptide was isolated from 7000 brains of the desert locust. Schistocerca gregaria by screening of HPLC fractions using a RIA for Dip-AST-2 (allatostatin-2 from the cockroach). Maldi-TOF-MS revealed a mass of 921.4 Da. The primary structure of the peptide is LPVYNFGL-NH2. It is identical to the C-terminal portion of schistostatin-2 from Schistocerca gregaria. Therefore, it was designated Scg-AST-2(11-18). The chromatographic properties of the synthetic peptide are identical to these of the native peptide. The peptide is a truncated product of Scg-AST-2, suggesting that an endopeptidase which cleaves between Arg and Leu is present in the brain complex of S. gregaria. Although, Scg-AST-2(11-18) contains the same C-terminus as Dip-AST-2, it has no inhibitory activity on the corpora allata (CA) of 2-day-old virgin females of D. punctata. This suggests that Scg-AST2 (11-18) may be the result of a proteolytic inactivation mechanism and/or that it may be involved in stage-dependent down regulation of allatostatic activity. To our knowledge, Scg-AST-2 is the first isolated peptide which has the active core of the allatostatin peptide family but nevertheless shows no activity in this bioassay.
Veelaert
D
D
Zoological Institute, Katholieke Universiteit Leuven, Belgium.
Devreese
B
B
Vanden Broeck
J
J
Yu
C G
CG
Schoofs
L
L
Van Beeumen
J
J
Tobe
S S
SS
De Loof
A
A
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003058:Cockroaches / Q000187:drug effects; D003335:Corpora Allata / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006110:Grasshoppers / Q000737:chemistry*; D019476:Insect Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D007605:Juvenile Hormones / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D017421:Sequence Analysis
D000596:Amino Acids; D019476:Insect Proteins; D007605:Juvenile Hormones; D009479:Neuropeptides; D010455:Peptides; C103956:schistostatin