Isolation of Ala1-proctolin, the first natural analogue of proctolin, from the brain of the Colorado potato beetle.
Methanolic head and brain extracts of the Colorado potato beetle contain several myotropins, active in the Locusta oviduct motility assay. Reversed phase high performance liquid chromatography (RP HPLC) gave evidence for the presence of three myotropic factors, with retention times close to that of proctolin. Both strongly stimulated the frequency, amplitude and tonus of the myogenic oviduct contractions. Gas phase sequencing and FAB-MS revealed that, besides proctolin (Arg-Tyr-Leu-Pro-Thr), two natural proctolin analogues were present. The first one is Ala-Tyr-Leu-Pro-Thr and is designed as Ala1-proctolin. The threshold concentration for biological activity of Ala1-proctolin was 10(-7) M, compared to 10(-10) M for proctolin itself. Ala1-proctolin is the first identified biological analogue of proctolin. The full nature of the first amino acid of a third proctolin-analogue (x-Tyr-Leu-Pro-Thr) is probably a modified amino acid of which the identity could as yet not be revealed. Our results suggest the existence of a family of proctolin-like peptides.
Spittaels
K
K
Zoologisch Instituut, Katholieke Universiteit Leuven, Belgium.
Vankeerberghen
A
A
Torrekens
S
S
Devreese
B
B
Grauwels
L
L
Van Leuven
F
F
Hunt
D
D
Shabanowitz
J
J
Schoofs
L
L
Van Beeumen
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D001517:Coleoptera; D000432:Methanol; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000737:chemistry / Q000302:isolation & purification*; D009842:Oligopeptides / Q000737:chemistry / Q000302:isolation & purification*; D016339:Spectrometry, Mass, Fast Atom Bombardment
D009479:Neuropeptides; D009842:Oligopeptides; C095679:alanyl-tyrosyl-leucyl-prolyl-threonine; C011536:proctolin; D000432:Methanol