Elastin elastic fiber

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

This coacervation process forms the basis for the self-assembly, which takes place prior to the crosslinking. The assembly of tropoelastin is based on an ordering process, in which the polypeptides are converted from a state with little order to a more structured conformation [8]. The insoluble elastic fiber is formed via the enzymatic crosslinking of tropoelastin (described in Sect. 2.1). Various models have been proposed to explain the mechanism of elasticity of the elastin fibers. 

Many tissues, such as lung, blood vessels, and skin, require elasticity for proper function this property is fulfilled by the matrix elastic fibers, which are composed of the proteins elastin and fibrillin. 

The pattern of inheritance of Marfan syndrome is autosomal dominant due to the failure of elastic fibers to assemble properly upon interaction of mutant fibrillin with normal elastin. 

Function and location of elastin Cause of Marfan syn drome Elastin is a connective tissue protein with rubber-like properties. Elastic fibers composed of elastin and glycoprotein microfibrils, such as fibrillin, are found in the lungs, the walls of large arteries, and elastic ligaments. [Note Mutations in the fibrillin gene are responsible for Marfan syndrome]... 

The tight y turn215 and the proline-containing P turn shown in Fig. 2-24 are thought to be major components of the secondary structure of elastin.216-218 This stretchable polymer, which consists largely of nonpolar amino acids, is the most abundant protein of the elastic fibers of skin, lungs, and arteries. The... 

Ehlers-Danlos syndrome 438 Eicosanoid 565 Eigen, Manfred 84 Elastase 66,609,610,611s cryoenzymology 616 P-cylinder in 78 Elastic fibers 436 Elastin 15,72,436 Electrical double layer 400 Electric field jump methods 468 Electrochemical gradient 410 Electrochemical transference 311 Electrode(s)... 

Fibrillin microfibrils are widely distributed extracellular matrix assemblies that endow elastic and non elastic connective tissues with long-range elasticity. They direct tropoelastin deposition during elastic fibrillogenesis and form an outer mantle for mature elastic fibers. Microfibril arrays are also abundant in dynamic tissues that do not express elastin, such as the ciliary zonules of the eye. Mutations in fibrillin-1—the principal structural component of microfibrils—cause Marfan syndrome, a heritable disease with severe aortic, ocular, and skeletal defects. Isolated fibrillin-rich microfibrils have a complex 56 nm beads-on-a-string appearance the molecular basis of their assembly and... 

Elastogenesis occurs primarily during late fetal and early neonatal periods. Elastin is synthesized and secreted from several cell types including smooth muscle cells, fibroblasts, endothelial cells, chondroblasts, and mesothelial cells (Uitto et al, 1991) with tissue-specific induction of elastin expression during development (Swee et al, 1995). After elastin has been deposited, its synthesis ceases and very little turnover of elastin is seen during adult life, unless the elastic fibers are subject to injury. In this case,... 

Macroscopically, elastin appears to be an amorphous mass. Ultrastruc-tural electron microscopy studies reveal that elastin has a fibrillar substructure comprised of parallel-aligned 5nm thick filaments that appear to have a twisted ropelike structure (Gotte et al., 1974 Pasquali-Ronchetti et al, 1998). A variety of techniques have been used to resolve these filaments, including negative staining electron microscopy of sonicated fragments of purified elastic fibers (Serafini-Fracassini et al., 1976), freeze... 

Bressan, G. M., Daga-Gordini, D., Colombatti, A., Castellani, I., Marigo, V., and Volpin, D. (1993). Emilin, a component of elastic fibers preferentially located at the elastin-microfibrils interface. /. Cell Biol. 121, 201-212. 

Brown-Augsburger, P. B., Broekelmann, T., Rosenbloom, J., and Mecham, R. P. (1996). Functional domains on elastin and MAGP involved in elastic fiber assembly. Biochem. J. 318, 149-155. 

Faury, G. (2001). Function-structure relationship of elastic arteries in evolution From microfibrils to elastin and elastic fibers. Pathol. Biol. 49, 310-325. 

Yanagisawa, H., Davis, E. C., Starcher, B. C., Ouchi, T., Yanagisawa, M., Richardson, J. A., and Olson, E. N. (2002). Fibulin-5 is an elastin-binding protein essential for elastic fiber development in vivo. Nature 415, 168-171. 

Elastin Protein Amino acids Structureless component of elastic fibers... 

Elastic fibers form the network in skin and cardiovascular tissue (elastic arteries) that is associated with elastic recovery. Historically the recovery of skin and vessel wall on removal of mechanical loads at low strains has been attributed to elastic fibers. Elastic fibers are composed of a core of elastin surrounded by microfibrils 10 to 15 nm in diameter composed of a family of glycoproteins recently termed fibrillins. Fibrillins are a family of extracellular matrix glycoproteins (MW about 350,000) containing a large number of cysteine residues (cysteine residues form disulfide crosslinks). Several members of the family have been described. The common molecular features include N and C terminal ends with 47 tandemly repeated epi-... 

Elastin is typically considered as an amorphous protein consisting of random chain sequences connected by a helical regions. The elastin content varies in elastic fibers such as those found in skin. Elastic fibers are termed oxytalan fibers in the upper dermal layer of skin and they are termed elaunin fibers in the deeper dermis where their elastin content is higher. In vessel wall elastic fibers have recently been differentiated based on histological staining patterns suggesting that differences in mechanical properties of different vessel walls may in part be due to differences in elastin... 

The other major protein in the extracellular matrix is elastin, which is the main component of elastic fibers found in ligaments, large arteries, and lungs. After synthesis and partial hydroxylation of proline residues, a 72 kDa molecule of tropoelastin is secreted into the matrix. This protein is rich in nonpolar amino acids and contains repeating sequences, such as (Val-Pro-Gly-Val-Gly). These sections form an amorphous, random-coiled structure with frequent reverse turns. Other recurrent sequences are rich in alanine with paired lysine residues, e.g., -Ala-Ala-Ala-Ala-Lys-Ala-Ala-Lys-... 

The amorphous elastin is organized into elastic fibers with a sheath of microfibrils surrounding each 10 nm fiber. The major component of the sheath is the glycoprotein fibrillin, mutations in whose gene causes Marfan syndrome. 

For purposes of definition, we will use the following terms to designate the various forms of elastin. The term, non-cross-linked elastin, will be used as a general description for proposed precursors to mature elastin that appear to be rapidly modified during the initial stages of elastic fiber formation. 

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