Physalaemin

Physalaemin
Identifiers
CAS Number
ChEMBL
MeSH Physalaemin
PubChem CID
UNII
Properties
Chemical formula
 C58H84N14O16S
Molar mass 1265.44 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Physalaemin is a tachykinin peptide obtained from the Physalaemus frog, closely related to substance P. Its structure was first elucidated in 1964.[1][2]

Like all tachykinins, physalaemin is a sialagogue (increases salivation) and a potent vasodilator with hypotensive effects.[3]

Structure

Physalaemin (PHY) is known to take on both a linear and helical three dimensional structure. Grace et al. (2010) have shown that in aqueous environments,  PHY preferentially takes on the linear conformation whereas in an environment that simulates a cellular membrane, PHY takes on a helical confirmation from the Pro4 residue to the C-Terminus. This helical conformation is essential to allow the binding of PHY to neurokinin-1 (NK1) receptors. Consensus sequences between Substance P (a mammalian tachykinin and agonist of NK1) and PHY have been used to confirm that the helical confirmation is necessary for PHY to bind to NK1.[4]

Use In Research

Not only is PHY closely related to Substance P (SP), but it also has a higher affinity for the mammalian neurokinin receptors that Substance P can bind to. Researchers can make use of this behavior of PHY to study the behavior of smooth muscle -  a tissue where NK1 can be found. Shiina et al. (2010) used PHY to show that tachykinins as a whole can cause the longitudinal contraction of smooth muscle tissue in esophageal tissue.[5]

Singh et Maji made use of PHY's similarity to SP along with its sequence similarity to Amyloid B-peptide 25-35 [AB(25-35)]. Despite its sequence similarity to SP, Singh et Maji showed that PHY had distinct amyloid forming capabilities . Under artificially elevated concentrations of tetrafluoroethylene (TFE) and a short incubation time, PHY was able to form amyloid fibrils. These fibrils originating from tackynins like PHY were also shown to reduce the neurotoxicity of other Amyloid fibers associated with amyloid induced diseases such as  Alzheimer's disease.[6]

References

  1. ↑ Erspaemer V, Anastasi A, Bertaccini G, Cei JM (1964). "Structure and pharmacological actions of physalaemin, the main active polypeptide of the skin of Physalaemus fuscumaculatus". Experientia. 20 (9): 489–90. doi:10.1007/BF02154064. PMID 5857249. S2CID 25448266.
  2. ↑ Anastasi A, Erspamer V, Cei JM (1964). "Isolation and amino acid sequence of physalaemin, the main active polypeptide of the skin of Physalaemus fuscumaculatus". Arch Biochem Biophys. 108 (2): 341–8. doi:10.1016/0003-9861(64)90395-9. PMID 14240587.
  3. ↑ Severini C, Improta G, Falconieri-Erspamer G, Salvadori S, Erspamer V (2002). "The tachykinin peptide family". Pharmacol Rev. 54 (2): 285–322. doi:10.1124/pr.54.2.285. PMID 12037144. S2CID 85570180.
  4. ↑ Grace, Christy Rani R.; Cowsik, Sudha Mahajan (2011). "Solution conformation of non-mammalian tachykinin physalaemin in lipid micelles by nuclear magnetic resonance". Biopolymers. 96 (3): 252–259. doi:10.1002/bip.21519. PMID 20632396.
  5. ↑ Shiina, Takahiko; Shima, Takeshi; Hirayama, Haruko; Kuramoto, Hirofumi; Takewaki, Tadashi; Shimizu, Yasutake (February 2010). "Contractile responses induced by physalaemin, an analogue of substance P, in the rat esophagus". European Journal of Pharmacology. 628 (1–3): 202–206. doi:10.1016/j.ejphar.2009.11.039. PMID 19958761.
  6. ↑ Singh, Pradeep K.; Maji, Samir K. (September 2012). "Amyloid-Like Fibril Formation by Tachykinin Neuropeptides and Its Relevance to Amyloid β-Protein Aggregation and Toxicity". Cell Biochemistry and Biophysics. 64 (1): 29–44. doi:10.1007/s12013-012-9364-z. ISSN 1085-9195. PMID 22628076. S2CID 17460410.


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