Elastin common amino acid sequences

COMMON AMINO ACID SEQUENCES IN NON-CROSSLINKED ELASTIN. 

Amino acid sequences of specific tryptic peptides found in porcine tropoelastin. When tentative assignments are given, the designations are in parentheses. The common repeating units are underlined. In certain instances liberty was taken in defining a common repeating unit when there was only amino acid difference. These sequences are common to the extensible regions in elastin. The tetra, penta or hexa repeats appear to correspond to 15 to 25 percent of the total residues in the protein. The source for the sequence data is reference 1. 

Figure 5 Amino acid sequences of common silklike-elastin-like multiblock copolymers, (a) SELP-47K (M = 69,814 Da), (b) SELP-415K-6-mer (Mw = 55,130 Da), (c) SELP-415K-8-mer (M = 71,500 Da), and (d) SELP-415K-10-mer (M = 87,860 Da). Adapted with permission from Haider, M. Leung, V. Eerrari, E. Crissman, J. Powell, J. Cappello, J. Ghandehari, H. Molecular Pharmaceutics 2M5, 2,139-150.

Elastin-like polypeptides (ELPs) have been extensively studied due to the fact that they combine similar stimulus response properties to other artificial polymers such as poly(iV-isopropylacrylamide) (pNIPAM) with the advantages of a biologically derived material, that is, it is biocompatible, modular in its composition, and can be obtained by biological processes. ELPs are polypeptides that contain a short, repetitive peptide sequence, most commonly (VPGXG) that is derived from tropoelastin, the precursor of elastin. In this sequence, X represents any amino acid sequence except proline. Polypeptides composed of the pentapeptide repeat unit VPGXG possess a reversible lower critical solution temperature (LCST). Below the LCST, the peptide is soluble... 

As shown in Table 3, in aqueous solution these short resilin-like peptides adopt a mixture of PPII stmcture, unordered conformations, and p-tums, while in Ttifluoroethanol (TFE) primarily type-11 p tums populate the conformational space. These findings are consistent with what Andersen has predicted and are also very similar to other elastomeric proteins studied. Interestingly, coacervation, a common phenomenon in elastin and abductin (in which a protein-rich phase is formed when the temperature is raised), has not been observed in resilin-like polypeptides (RLPs). This is almost certainly due to the inaeased hydrophilicity of resilin, which is soluble in water under all relevant experimental conditions. As mentioned above, additional spectroscopic studies on extended RLPs, as well as manipulations of RLP sequences via the introduction of different amino acid analogs and evaluation of corresponding conformational changes, would be useful to elucidate the mechanism of elasticity of resilin. 

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