Open AccessPost‐translational modifications of the insect sulfakinins
Author(s) -
Predel Reinhard,
Brandt Wolf,
Kellner Roland,
Rapus Jürgen,
Nachman Ronald J.,
Gäde Gerd
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00532.x
Subject(s) - periplaneta , cockroach , hindgut , corpus allatum , edman degradation , american cockroach , peptide , chemistry , biochemistry , insect , biology , peptide sequence , midgut , botany , juvenile hormone , ecology , larva , gene
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 ≈ 5 × 10 −10 m (heart) and 2 × 10 −9 m (hindgut).