Contryphan

The contryphans (conus + tryptophan) are a family of peptides which are active constituents of venom produced by cone snail (genus conus). The two cysteine residues in contryphans are linked by a disulfide bond. In addition, contryphans undergo an unusual degree of post-translational modification including epimerization of leucine and tryptophan, tryptophan bromination, amidation of the C-terminus, and proline hydroxylation.

Family members
Contryphan family members include:

where
 * O =4-trans-hydroxyproline
 * l = D-leucine
 * L = L-leucine
 * w = D-tryptophan
 * W = L-tryptophan
 * γ = gamma-carboxyglutamic acid

Mechanism of toxicity
The venom of cone snails cause paralysis of their fish prey. The molecular target has not been determined for all contryphan peptides however it is known that contryphan-Vn is a Ca2+-dependent K+ channel modulator, while glacontryphan-M is a L-type calcium channel blocker.