Elastin elasticity/flexibility

Resilin and elastin, unlike other structural proteins, fulfill both definitions of an elastic material. Colloquially speaking, resilin and elastin are stretchy or flexible. They also fulfill the strict definition of an elastic material, i.e., the ability to deform in proportion to the magnitude of an applied stress without a loss of energy, and the recovery of the material to its original state when that stress is removed. Resilin and elastin are alone in the category of structural proteins (e.g., collagen, silk, etc.) in that they have the correct blend of physical properties that allow the proteins to fulfill both definitions of elasticity. Both proteins have high extensibility and combine that property with remarkable resilience [208]. 

Collagens (see p. 344), of which there are at least 19 different varieties, form fibers, fibrils, networks, and ligaments. Their characteristic properties are tensile strength and flexibility. Elastin is a fiber protein with a high degree of elasticity. 

Beneath the stratum corneum, the dermis (or corneum) is a tough supportive connective-tissue matrix, containing specialised structures and a substantial vascular supply. The dermis varies in thickness, being thin (0.6 mm) on the back of the eyelids and thicker (3 mm or more) on the back, palms and soles. The dermis provides flexibility and elasticity to the skin. Its major components are collagen, reticulin, elastin and fibres, and ground substance. The ground... 

Elastin is the protein found in elastic tissues such as tendons and arteries. The polypeptide chain of elastin is rich in alanine and glycine and is very flexible. It contains cross-links involving lysine side chains, which prevent the protein from extending excessively under tension and allow it to return to its normal length when tension is removed. 

Copper provides the essential functional part of a number of enzymes involved in oxidation and reduction reactions, including dopamine P-hydroxylase in the synthesis of noradrenaline and adrenaline, cytochrome oxidase in the electron transport chain (section 3.3.1.2) and superoxide dismutase, one of the enzymes involved in protection against oxygen radicals (section 7.4.3.1). Copper is also important in the oxidation of lysine to form the cross-links in collagen and elastin. In copper deficiency the bones are abnormally fragile, because the abnormal collagen does not permit the normal flexibility of the bone matrix. More importantly, elastin is less elastic than normal and copper deficiency can lead to death following rupture of the aorta. 

In connective tissue collagen coexists with elastin, a protein of quite different character, though also rich in proline and glycine. Elastin takes the form of a highly flexible random coil. Separate polypeptide chains are chemically linked to one another at intervals through certain of the side chains, to form an elastic net. When made into a fibre, elastin can be stretched at least five times... 

So, at high temperatures, the ELP is a highly flexible chain, which shows a random distribution of the end-to-end distance in agreement with the idea of Hoeve and Flory that the elasticity of elastin is rubber like [662, 663]. Irregular (or even random) location of the ordered... 

Polymer networks are conveniently characterized in the elastomeric state, which is exhibited at temperatures above the glass-to-rubber transition temperature T. In this state, the large ensemble of configurations accessible to flexible chain molecules by Brownian motion is very amenable to statistical mechanical analysis. Polymers with relatively high values of such as polystyrene or elastin are generally studied in the swollen state to lower their values of to below the temperature of investigation. It is also advantageous to study network behavior in the swollen state since this facilitates the approach to elastic equilibrium, which is required for application of rubber elasticity theories based on statistical thermodynamics. ... 

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