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Mass spectral signature for insect adipokinetic hormones
Author(s) -
König Simone,
Albers Christian,
Gäde Gerd
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2167
Subject(s) - chemistry , electrospray ionization , mass spectrometry , ion , adipokinetic hormone , amino acid , stereochemistry , chromatography , biochemistry , organic chemistry , fat body , gene
Insect adipokinetic hormones (AKHs) are structurally similar. They consist of 8 to 10 amino acid residues, and are post‐translationally modified at the N‐terminus (pyroglutamic acid) and at the C‐terminus (carboxyamide). They contain aromatic amino acids at position 4 (mostly Phe, in a few cases Tyr) and at position 8 (Trp). Position 9 is always Gly which is used in the octapeptides for the amidation, and the majority of the peptides have no charge. AKHs exhibit a characteristic ion signature both in matrix‐assisted laser desorption/ionization (ion pair [M+Na] + /[M+K] + ) and in electrospray mass spectrometry ([M+H+K] 2+ , [M–17+H] + , [M+H] + , [M+Na] + , [M+K] + ). Their high affinity for Na + and K + alkali cations is observed even after reversed‐phase purification. AKHs rarely form doubly charged ions with protons or sodium while the [M+H+K] 2+ ion is often abundant suggesting a special conformation of the larger metal ion complex possibly related to its size. Here, we present analyses of several AKHs of different insect species and discuss their ionization behavior with respect to their sequence. The mass spectral signature observed is useful for AKH detection from mixtures and so an unassigned 990.7 Da molecule was found in dragonfly which is currently under investigation. Copyright © 2005 John Wiley & Sons, Ltd.