Potencies of naturally-occurring AKH/RPCH peptides in Locusta migratoria in the acetate uptake assay in vitro and comparison with their potencies in the lipid mobilisation assay in vivo.
The biological potencies of a number of naturally-occurring octa- and decapeptides of the large AKH/RPCH family of peptides were determined in Locusta migratoria using the lipid-mobilising assay in vivo and the acetate uptake assay in vitro. The most potent of the newly-tested peptides in the in vitro assay, Phl-CC, differs from the endogenous major locust peptide, Lom-AKH-I, only by an exchange of serine versus threonine at position 10. However, the most active peptide in the in vitro assay remains Lom-AKH-III. At the other extreme is the peptide Mem-CC which contains a tyrosine residue at position 4 rather than the more typical phenylalanine. This peptide is over 20,000 times less potent than Lom-AKH-III in the in vitro assay, and also results in an unusual dose-response curve in the in vivo assay. Only a few peptides are approximately equipotent in both assays, but mostly the bioanalogues have a higher potency in vitro. The majority of them are 2- to 10-fold more potent in vitro, but Ani-AKH and Lom-AKH-III are 19- and 48-fold more potent. The results are discussed in relation to either the actions of proteases or of possible preferential binding of different receptors involved in the different assays.
Gäde
G
G
Zoology Department, University of Cape Town, Rondebosch, South Africa. ggade@botzoo.uct.ac.za
Lee
M J
MJ
Goldsworthy
G J
GJ
Kellner
R
R
D019342:Acetic Acid / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D005260:Female; D006110:Grasshoppers / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D007301:Insect Hormones / Q000737:chemistry / Q000494:pharmacology*; D050356:Lipid Metabolism; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives
D007301:Insect Hormones; D009842:Oligopeptides; C022059:red pigment-concentrating hormone; C014956:adipokinetic hormone (locust); D019342:Acetic Acid; D011761:Pyrrolidonecarboxylic Acid