Contryphan

The contryphans (conus + tryptophan) are a family of peptides that are active constituents of the potent venom produced by cone snail (genus Conus). The two amino acid 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.[2] In the broader scheme of genetic conotoxin classification, contryphans are members of "Conotoxin Superfamily O2."[3]

Contryphan
NMR structure of Contryphan-Vn. The peptide backbone is depicted by a curved tube while the amino acid side-chains are represented by capped sticks. Carbon atoms are colored grey, nitrogen atoms blue, oxygen atoms red, and sulfur atoms yellow.[1]
.
Identifiers
SymbolContryphan_CS
PfamPF02950
InterProIPR011062
PROSITEPS60027
SCOPe2cco / SUPFAM

Family members
Conus textile, which produces contryphans

Contryphan family members include:

Peptide Sequence Species Reference
Des(Gly1)contryphan-R COwEPWC-NH2 C. radiatus [4]
Contryphan-R GCOwEPWC-NH2 Conus radiatus [4]
Bromocontyphan-R GCOwEPXC-NH2 C. radiatus [5]
Contryphan-Sm GCOwQPWC-NH2 Conus stercusmuscarum [6]
Contryphan-P GCOwDPWC-NH2 C. purpurascens [6]
Contryphan-R/Tx GCOwEPWC-NH2 Conus textile [6]
Contryphan-Tx GCOWQPYC-NH2 Conus textile [6]
Contryphan-Vn GDCPwKPWC-NH2 Conus ventricosus [7]
Leu-contryphan-P GCVlLPWC-OH Conus purpurascens [8]
Leu-contryphan-Tx CVlYPWC-NH2 Conus textile [6]
Glaconryphan-M NγSγCPWHPWC-NH2 Conus marmoreus [2]

where the sequence abbreviations stand for:

and the remainder of the letters refer to the standard one letter abbreviations for amino acids.

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,[7] while glacontryphan-M is a L-type calcium channel blocker.[2]

gollark: That wouldn't stop this sort of attack from working.
gollark: There are other possible uses, though. Someone with illegal material could just set the hash to some random value without making the image look particularly weird.
gollark: Maybe something something adverserial image scaling, if it's implemented poorly.
gollark: It's probably harder to break without the image looking noticeably different, though, since it just works by downscaling and grayscaling things or something.
gollark: That is entirely possible.

References
  1. PDB: 1NXN​; Eliseo T, Cicero DO, Romeo C, Schininà ME, Massilia GR, Polticelli F, Ascenzi P, Paci M (June 2004). "Solution structure of the cyclic peptide contryphan-Vn, a Ca2+-dependent K+ channel modulator". Biopolymers. 74 (3): 189–98. doi:10.1002/bip.20025. PMID 15150794.
  2. Hansson K, Ma X, Eliasson L, Czerwiec E, Furie B, Furie BC, Rorsman P, Stenflo J (July 2004). "The first gamma-carboxyglutamic acid-containing contryphan. A selective L-type calcium ion channel blocker isolated from the venom of Conus marmoreus". The Journal of Biological Chemistry. 279 (31): 32453–63. doi:10.1074/jbc.M313825200. PMID 15155730.
  3. Robinson SD, Norton RS (December 2014). "Conotoxin gene superfamilies". Marine Drugs. 12 (12): 6058–101. doi:10.3390/md12126058. PMC 4278219. PMID 25522317.
  4. Jimenéz EC, Olivera BM, Gray WR, Cruz LJ (November 1996). "Contryphan is a D-tryptophan-containing Conus peptide". The Journal of Biological Chemistry. 271 (45): 28002–5. doi:10.1074/jbc.271.45.28002. PMID 8910408.
  5. Jimenez EC, Craig AG, Watkins M, Hillyard DR, Gray WR, Gulyas J, Rivier JE, Cruz LJ, Olivera BM (February 1997). "Bromocontryphan: post-translational bromination of tryptophan". Biochemistry. 36 (5): 989–94. doi:10.1021/bi962840p. PMID 9033387.
  6. Jacobsen R, Jimenez EC, Grilley M, Watkins M, Hillyard D, Cruz LJ, Olivera BM (March 1998). "The contryphans, a D-tryptophan-containing family of Conus peptides: interconversion between conformers". The Journal of Peptide Research. 51 (3): 173–9. doi:10.1111/j.1399-3011.1998.tb01213.x. PMID 9531419.
  7. Massilia GR, Schininà ME, Ascenzi P, Polticelli F (November 2001). "Contryphan-Vn: a novel peptide from the venom of the Mediterranean snail Conus ventricosus". Biochemical and Biophysical Research Communications. 288 (4): 908–13. doi:10.1006/bbrc.2001.5833. PMID 11688995.
  8. Jacobsen RB, Jimenez EC, De la Cruz RG, Gray WR, Cruz LJ, Olivera BM (August 1999). "A novel D-leucine-containing Conus peptide: diverse conformational dynamics in the contryphan family". The Journal of Peptide Research. 54 (2): 93–9. doi:10.1034/j.1399-3011.1999.00093.x. PMID 10461743.
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