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Esculentin-2CHa is an antimicrobial peptide which is located outside the cells membranes of the skin epithelium of many species of amphibis, such as Rana chiricahuensis. This protein has recently become more important due to its defense response function and lately, its possible application in the treatment of human pathologies, has been studied in research.

Primary structure Esculentin-2Cha is made of thirty-seven amino acids, four of which are aliphatic hydrophobic like Alanina or Leucina and one of which is aromatic hydrophobic Fenilalanina. There’s also positive amino acids like Arginine or Lysine and a negative one: Aspirin. The other ones, such as Serine Cysteine and Glutamine, are polar with no-charge. Thanks to the evolutionary pressure, the N-terminal hexapeptide sequence has kept its hydrophobic character, even though the primary structure of esculentin-2 in frog species hasn’t mantain properly.

Secondary structure Esculentin’s secondary structure is stood on helix/coil transition theory it’s usually forming a conformation as an extended amphipathic helical in the residues from 17 to 33. On the one hand, replacement of the Cys31 and Cys37 residues of the cyclic domain at the C-terminus of the esculentin by isosteric I-serine, outcomes an analog with decreasing helicity. On the other hand, removing from the N-terminus of the peptide, it creates fragments with extended-helical conformation; however, they aren’t as hydrophobic and cationic than the natural one.