Open AccessIsolation and chemical characterization of a novel insulin‐related neuropeptide from the freshwater snail, Lymnaea stagnalis
Author(s) -
LI Ka,
GERAERTS Wijnand P. M.
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb16828.x
Subject(s) - lymnaea stagnalis , edman degradation , peptide , lymnaea , peptide sequence , amino acid , biology , biochemistry , snail , gene , ecology
A novel molluscan insulin‐related peptide (MIP) III, has been isolated from alcohol extracts of the neurohaemal area of the cerebral neuroendocrine light‐green neurones of Lymnaea stagnalis . MIP III was purified by sequential high‐performance gel‐permeation chromatography followed by reverse‐phase HPLC. MIP III is a heterodimer connected by disulphide bonds. Edman degradation analysis and subsequent alignment with the A and B chains of the previously identified MIP I and II showed that the 24‐amino‐acid peptide with the sequence pQSRPSIVC(E)CCFNQCTVQ(E)LLAYC represents the MIP III A chain, and the 37‐amino‐acid peptide sequence TTQHTCSILSRPHPRGLCGSTLANMVQWLCSTYTTSS the B chain. The overall amino acid sequence of MIP III shows about 50% similarity with those of MIP I and II, and only 20–40% similarity with other peptides of the insulin superfamily. Important structural features, e.g. disulphide bridges and the hydrophobic core, are conserved in MIP III.