Temperature-correlated force and structure development in elastomeric polypeptides: The Ile1 analog of the polypentapeptide of elastin

✍ Scribed by D. W. Urry; M. M. Long; R. D. Harris; K. U. Prasad

• Publisher: Wiley (John Wiley & Sons)
• Year: 1986
• Tongue: English
• Weight: 1014 KB
• Volume: 25
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360251009

✦ Synopsis

Synopsis

The Ile' analog of the polypentapeptide of elastin, (L' Ile'-L-Pro2-Gly3-~.Val4-G1y5),, abbreviated as I k -P P P , was synthesized with n > 100 to determine the effect of the increased hydrophobicity of the pentamer resulting from Val' replacement by Ile' on the previously characterized inverse temperature transition of the polypentapeptide of elastin (PPP). Ile' -PPP, dissolved in water at 4"C, was found to aggregate, forming a viscoelastic coacervate on raising the temperature. The onset of aggregation was 8°C for I k -P P P , as compared to 24°C for PPP. Characterization by CD demonstrated an increase in intramolecular order on raising the temperature from 8°C to 25"C, and demonstrated similar conformations for PPP and He'-PPP before and after their respective transitions. The CD-characterized transition also occurred at a temperature some 15°C lower than that of PPP. By means of 20-Mrad yirradiation cross-linking of the I k -P P P coacervate, an elastomeric matrix was formed with an elastic modulus, similar to that of 20-Mrad crosslinked PPP. The temperature dependence of elastomeric force of cross-linked Ile'-PPP showed an abrupt increase from essentially zero at 8°C to three-quarters of full force at 10°C and essentially full force by 20-25°C. This development of elastomeric force for the more hydrophobic I k -P P P matrix, which paxallels the increase in intramolecular order characterized by the CD studies, also occurs at a temperature some 15°C lower than that for the PPP matrix. Thus, in these elastomeric polypeptides, development of elastomeric force is coupled to an inverse temperature transition, the temperature of which depends inversely on the hydrophobicity of the constituent pentamer. It appears that a series of elastomeric polypeptide biomaterials are possible in which the temperature over which elastomeric force develops can be varied.