Tachyplesin: Difference between revisions

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The sequence adapts an antiparallel β-sheet (hairpin) conformation in solution, with a <scene name='67/671725/Beta_turn_tp-1/2'>β-turn</scene> for the centrally located residues <scene name='67/671725/Tyrargglyile/3'>Tyr-Arg-Gly-Ile</scene>, stabilized by two cross-strand <scene name='67/671725/Disulfide_bonds/4'> disulfide bonds </scene>  between Cys³-Cys¹⁶ and Cys⁷-Cys¹²<ref name=Saravanan>PMID:22464970</ref><ref name=Nakamura>Nakamura, Takanori, et al. "Tachyplesin, a class of antimicrobial peptide from the hemocytes of the horseshoe crab (''Tachypleus tridentatus''). Isolation and chemical structure." Journal of Biological Chemistry 263.32 (1988): 16709-16713</ref>, and [http://en.wikipedia.org/wiki/Protein_primary_structure C-terminus amidation].  In addition there are H-bonds and aromatic rings stacking interactions which helps stabilize the hairpin loop structure of the peptide.  
The sequence adapts an antiparallel β-sheet (hairpin) conformation in solution, with a <scene name='67/671725/Beta_turn_tp-1/2'>β-turn</scene> for the centrally located residues <scene name='67/671725/Tyrargglyile/3'>Tyr-Arg-Gly-Ile</scene>, stabilized by two cross-strand <scene name='67/671725/Disulfide_bonds/4'> disulfide bonds </scene>  between Cys³-Cys¹⁶ and Cys⁷-Cys¹²<ref name=Saravanan>PMID:22464970</ref><ref name=Nakamura>Nakamura, Takanori, et al. "Tachyplesin, a class of antimicrobial peptide from the hemocytes of the horseshoe crab (''Tachypleus tridentatus''). Isolation and chemical structure." Journal of Biological Chemistry 263.32 (1988): 16709-16713</ref>, and [http://en.wikipedia.org/wiki/Protein_primary_structure C-terminus amidation].  In addition there are H-bonds and aromatic rings stacking interactions which helps stabilize the hairpin loop structure of the peptide.  
   
   
TP-I undergoes a conformational change in the <scene name='67/671725/Tp_i_in_the_presence_of_lps/1'>presence of LPS </scene>. The backbone of the polypeptide becomes <scene name='67/671725/Conformation_change/6'>more rigid and twisted in the presence of LPS, than in the presence of water</scene>, making it more stable.
TP-I undergoes a conformational change in the <scene name='67/671725/Tp_i_in_the_presence_of_lps/1'>presence of LPS </scene>. The backbone of the polypeptide becomes <scene name='67/671725/Conformation_change/5'>more rigid and twisted in the presence of LPS, than in the presence of water</scene>, making it more stable.




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Among all the existing interactions, cysteine bridge being considered as the principal contributor of the structure, three linear derivatives of TP-I (<scene name='67/671725/1ma4/3'>TPY4</scene>, TPF4 and TPA4) were created, in which the bridging cysteine residues are uniformly replaced with tyrosine, phenylalanine, and alanine, respectively<ref name=Laederach>PMID:12369825</ref><ref name=Kushibiki>PMID:24389234</ref>. The linear derivatives of TP-I are mentioned below:
Among all the existing interactions, cysteine bridge being considered as the principal contributor of the structure, three linear derivatives of TP-I (<scene name='67/671725/1ma4/3'>TPY4</scene>, TPF4 and TPA4) were created, in which the bridging cysteine residues are uniformly replaced with tyrosine, phenylalanine, and alanine, respectively<ref name=Laederach>PMID:12369825</ref><ref name=Kushibiki>PMID:24389234</ref>. The linear derivatives of TP-I are mentioned below:


[[Image:Seq TPI.jpg]]
[[Image:Seq TPI.jpg|750px]]


Of those 3 linear derivatives of TP-I, NMR structural investigation had shown TPA4 to be unstructured in solution. Also, TPA4 was inactive in terms of antimicrobial activity. In contrast, TPY4 and TPF4 adapts hairpin loop and also had antimicrobial properties, typical to TP-I. Therefore, the hairpin properties of the peptide seems to be important for recognition of lipopolysaccharides and its biological activities.
Of those 3 linear derivatives of TP-I, NMR structural investigation had shown TPA4 to be unstructured in solution. Also, TPA4 was inactive in terms of antimicrobial activity. In contrast, TPY4 and TPF4 adapts hairpin loop and also had antimicrobial properties, typical to TP-I. Therefore, the hairpin properties of the peptide seems to be important for recognition of lipopolysaccharides and its biological activities.
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