Elastin model

Yamaoka T, Tamura T, Seto Y et al (2003) Mechanism for the phase transition of a genetically engineered elastin model peptide (vpgig)(40) in aqueous solution. Biomacromolecules 4 1680-1685... 

D.W. Urry,T. Hugel, M. Seitz, H. Gaub, L. Sheiba, J. Dea, J. Xu, L. Hayes, F. Prochazka, and T. Parker, Ideal Protein Elasticity The Elastin Model. In Elastomeric Proteins Structures, Biomechanical Properties and Biological Roles P.R. Shewry, A.S. Tatham, and A.J. Bailey, Eds. Cambridge University Press, The Royal Society Chapter Four, pages 54-93,2003. 

Description of the mechanics of elastin requires the understanding of two interlinked but distinct physical processes the development of entropic elastic force and the occurrence of hydrophobic association. Elementary statistical-mechanical analysis of AFM single-chain force-extension data of elastin model molecules identifies damping of internal chain dynamics on extension as a fundamental source of entropic elastic force and eliminates the requirement of random chain networks. For elastin and its models, this simple analysis is substantiated experimentally by the observation of mechanical resonances in the dielectric relaxation and acoustic absorption spectra, and theoretically by the dependence of entropy on frequency of torsion-angle oscillations, and by classical molecular-mechanics and dynamics calculations of relaxed and extended states of the P-spiral description of the elastin repeat, (GVGVP) . The role of hydrophobic hydration in the mechanics of elastin becomes apparent under conditions of isometric contraction. 

In an ideal or perfect elastomer the energy repeatedly invested in extension is repeatedly and completely recovered during relaxation. Ideality increases as the elastic force results from a decrease in entropy upon extension, because this occurs without stressing bonds to the breaking point. Elastin models and elastin itself in water provide examples of such entropic elastomers with about 90% of the elastic force being entropic, that is, the /e//ratio of Equation (4) is about 0.1. This is essential to human life expectancy, because the half-life of elastin in the mammalian elastic fiber is on the order of 70 years. This means that the elastic fibers of the aortic arch and thoracic aorta, where there is twice as much elastin as collagen, will have survived some billion demanding stretch-relaxation cycles by the start of the seventh decade of life. This represents an ultimate in ideal elasticity. 

Presence of Mechanical Resonances in Elastin Models and Elastin Itself... 

Entropy Calculations Based on the Elastin Model, (GVGVP) ... 

TAM Tamura, T., Yamaoka, T., Kimugi, S., Panitch, A., and Tirrell, D.A., Effects of temperature and pressme on the aggregation properties of an engineered elastin model polypeptide in aqueous solution. Biomacromolecules, 1, 552, 2000. 

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