Purification and structural characterization of a D-amino acid-containing conopeptide, conomarphin, from Conus marmoreus.

摘要: Cone snails, a group of gastropod animals that inhabit tropical seas, are capable producing mixture peptide neurotoxins, namely conotoxins, for defense and predation. Conotoxins mainly disulfide-rich short peptides act on different ion channels, neurotransmitter receptors, or transporters in the nervous system. They exhibit highly diverse compositions, structures, biological functions. In this work, novel Cys-free 15-residue conopeptide from Conus marmoreus was purified designated as conomarphin. Conomarphin is unique because its D-configuration Phe at third residue C-terminus, which identified using HPLC by comparing native conomarphin fragments corresponding synthetic cleaved proteases. Surprisingly, cDNA-encoded precursor found to share conserved signal with other M-superfamily clearly indicating should belong M-superfamily, although shares no homology six-Cys-containing conotoxins. Furthermore, NMR spectroscopy experiments established adopts well-defined structure solution, tight loop middle 3(10)-helix C-terminus. By contrast, L-Phe13-conomarphin found, suggests D-Phe13 essential conclusion, may represent new conotoxin family, whose activity remains be identified.