Rajaian P. Rajesh* and Jayaseelan B. Franklin Pages 1035 - 1040 ( 6 )
Background: Conotoxins are neuro-pharmacologically active cysteine rich peptides isolated from the venom complex of marine cone snails. These are usually made of even number of cysteines.
Method: In this study we characterised six novel conotoxin sequences from the venom of Conus leopardus collected from the Andaman Sea, namely Le907 (C-C), Le868 (C-C), Le933 (-C-CC), Le949 (-C-CC), Le1988 (C-C-CC-C) and Le1642 (CC-C-C) using de novo mass spectrometrybased sequencing methods. Astonishingly 3 of these peptides possess novel arrangements of cysteine residues with odd number of cysteines (-C-CC; C-C-CC-C), namely Le933, Le949 and Le1988. Further, a post-translational variant of peptide Le933 was identified and experimentally determined to contain hydroxyproline.
Results: The unusual cysteine arrangements observed suggests novel class of conotoxins. These results expand our understanding of the diversity of odd cysteine arrangements in conotoxins.
Cone snail, Conus leopardus, conotoxins, odd cysteines, novel cysteine arrangement, mass spectrometry.
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Atal Centre for Ocean Science and Technology, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103