Investigating by CD the molecular mechanism of elasticity of elastomeric proteins

Abstract

Elastomeric proteins are widespread in the animal kingdom, and their main function is to confer elasticity and resilience to organs and tissues. Besides common functional properties, elastomeric proteins share a common sequence design. They are usually constituted by repetitive sequences with a high content of glycine residues. From a conformational point of view, all the elastomeric proteins since now analyzed show a dynamic equilibria between folded (mainly beta-turns) and extended (polyproline II and beta-strands) conformations that could be at the origin of the high entropy of the relaxed state. As a matter of fact, elastin, lamprin, abductin, as well as the PEVK domain of titin share the same conformational ensemble, thus pointing to a common molecular mechanism as the origin of elasticity. CD spectroscopy represents the proper spectroscopic technique to be used overall because of its particular sensitivity to the presence of PPII structure. Its use in the molecular studies of elastin, abductin, and lamprin as well as the recently analyzed protein resilin will be presented.

Molecular and functional characterisation of resilin across three insect orders

“…All sets of spectra exhibit strong minima at 195e200 nm and, consistent with previous studies of elastomeric proteins and peptides including tropoelastin and resilin (Bochicchio et al, 2008), there is a trend for these minima to decrease in intensity as temperature is increased (Fig. 5B).…”

From bouncy legs to poisoned arrows: elastic movements in invertebrates

“…In contrast, resilin is thought to consist of unstructured domains and highly flexible poly-proline II structures moving in and out of a multiconformational equilibrium that acts as an entropic spring. When resilin is stretched, the resulting decrease in conformational entropy generates the restoring force with minimal energy loss (Bochicchio et al, 2008). The elastic recoil of abductin is thought to be driven in part by a similar mechanism as in resilin (Bochicchio et al, 2008), but also with a hydrophobic mechanism such that stretching the material reveals hydrophobic protein regions and the resting state returns to a conformation where the hydrophobic regions are sequestered from the aqueous environment (Tatham and Shewry, 2002).…”

“…When resilin is stretched, the resulting decrease in conformational entropy generates the restoring force with minimal energy loss (Bochicchio et al, 2008). The elastic recoil of abductin is thought to be driven in part by a similar mechanism as in resilin (Bochicchio et al, 2008), but also with a hydrophobic mechanism such that stretching the material reveals hydrophobic protein regions and the resting state returns to a conformation where the hydrophobic regions are sequestered from the aqueous environment (Tatham and Shewry, 2002). Thus, all of these materials rely on entropic forces to return to their resting state, but the underlying molecular arrangements and the use of hydrophibicity to mediate interactions with the surrounding medium in some systems, produce an impressive array of elastic material behaviors.…”

Investigating by circular dichroism some amyloidogenic elastin‐derived polypeptides

“…We demonstrated at molecular level, mainly by circular dichroism (CD), the existence of multiconformational equilibria among poly-L-proline II (PPII), b-turns, and unordered conformations. 5 At supramolecular level, we demonstrated that the polypeptide sequences encoded by the proline-rich domains are able to adopt the same behavior of the entire protein such as the coacervation. 6 Coacervation is an inverse phase-transition temperature-induced process that occurs at 378C for tropoelastin 7 and determines, at supramolecular level, the highly ordered filamentous organization of the protein.…”