Post-translational modifications of the insect sulfakinins. Sulfation, pyroglutamate-formation and O-methylation of glutamic acid

We identified and chemically characterized the two major forms of sulfakinins from an extract of 800 corpora cardiaca/corpora allata complexes of the American cockroach, Periplaneta americana. Bioactivity during the purification was monitored by measuring heart beat frequency in a preparation in sit...

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Published inEuropean journal of biochemistry Vol. 263; no. 2; pp. 552 - 560
Main Authors Predel, R, Brandt, W, Kellner, R, Rapus, J, Nachman, R.J, Gade, G
Format Journal Article
LanguageEnglish
Published England 01.07.1999
Subjects
Amino Acid Sequence
Animals
Chromatography, High Pressure Liquid
Cockroaches - chemistry
corpora allata
corpora cardiaca
Glutamic Acid - metabolism
Insect Proteins - metabolism
Male
Mass Spectrometry
Methylation
Molecular Sequence Data
neuropeptides
Neuropeptides - metabolism
Periplaneta americana
Protein Processing, Post-Translational
Pyrrolidonecarboxylic Acid - metabolism
sulfakinins
Time Factors
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Summary:We identified and chemically characterized the two major forms of sulfakinins from an extract of 800 corpora cardiaca/corpora allata complexes of the American cockroach, Periplaneta americana. Bioactivity during the purification was monitored by measuring heart beat frequency in a preparation in situ. By Edman degradation analysis and MS, these main forms were identified as having the primary structures Pea-SK [EQFDDY(SO(3)H)GHMRFamide] and Lem-SK-2 [pQSDDY(SO(3)H)GHMRFamide]. The sulfation was confirmed by UV, MS and peptide synthesis. In addition, post-translationally modified sulfakinins of both major forms were isolated and identified. Firstly, nonsulfated forms of these peptides are present in considerable amounts in the corpora cardiaca/allata. Secondly, the N-terminally blocked Pea-SK and the nonblocked Lem-SK-2 occur naturally in neurohaemal release sites. Thirdly, modified Pea-SK with O-methylated glutamic acid occurs which is not an artefact of peptide purification. The major forms of the sulfakinins were shown to be highly active on both the heart and hindgut with threshold concentrations of approximately 5 x 10(-10) M (heart) and 2 x 10(-9) M (hindgut).
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ISSN:0014-2956
1432-1033
DOI:10.1046/j.1432-1327.1999.00532.x