Elastic properties of protein fibers,

Biomechanical Machines. The mechanical properties of fibrous polypeptides could be put to use for the commercial production of fibers (qv) that are more elastic and resiUent than available synthetics (see Silk). The biochemical properties of proteins could also be harnessed for the conversion of mechanical energy to chemical energy (35). 

Industrial Uses. Papain is used in the leather industry to prepare the sides for tanning. Its proteolytic action removes some of the undesirable proteins which adhere to the hide and thus facilitates the subsequent tanning process. In the textile industry, the treatment of wool fibers with papain has been found to reduce the shrinkage from laundering. This appears to be caused by the abihty of the enzyme to destroy the elastic properties of wool protein. Because of its digestive action on protein, papain is used as a spot remover in the laundry and dry cleaning business. 

Elastase is the name given to proteinases that possess the ability to hydrolyze mature cross-linked elastin [18]. Elastin is an insoluble structural protein responsible for the elastic properties of the lung, skin, and arteries and is quite resistant to most proteinases. Elastin is high in hydrophobic amino acid residues such as valine, alanine, glycine, and proline [19]. Insoluble elastin fibers contain cross-links usually between four lysine residues, which form a unique cyclic product, desmosine. The presence of soluble desmosine cross-links in plasma can be used as a measure of elastin breakdown. Of all the elastases in humans, neutrophil elastase has received the most attention over the years due to its broad substrate specificity and abundance within the cell. However, neutrophils and macrophages contain several proteinases (Table 1), which are capable of degrading elastin. 

Barone and Schmidt (2005) reported on the use of keratin feather fiber as a short-fiber reinforcement in LDPE composites and showed that protein fibers have good resiliency and elastic recovery. Besides protein fibers have higher moisture regain and warmthness than natural ceUulosic fibers properties, all related to its possible use in earth material. The keratin feather fiber for these tests was obtained from chicken feather waste generated by the U.S. poultry industry (Galan-Marm et al. 2010). Clearly, water can play a very important role in these materials that can be elucidated using NMR spectroscopy however, this aspect was poorly studied. 

Measurement of mechanical properties of proteins, especially those of fibrous proteins, has been an important interdisciplinary concern in the history of protein science. In fact, the very early X-ray work by Astbury and his colleagues established the force dependent conformational transition of keratin fiber between a- and /3-forms [15]. A large body of work has since been accumulated on the measurement of mechanical parameters of fibrous structures made of keratin, collagen, dentin and other structural proteins [10, 14, 16, 17]. Measurement was done at the macroscopic level on higher order assemblies of fibrous proteins, applying established methods in materials science for the determination of, for example, static and/or dynamic elastic modulus [14],... 

Although the proteins in skin are also composed of about 5% elastic fibers, they do not appear to affect the mechanical properties of the tissue. The elastic fibers are believed to contribute to the recoil of the skin, which gives it the ability to be wrinkle-free when external loads are removed. As humans age, the elastic fiber network of the skin is lost, and wrinkles begin to appear. The mechanical role of the elastic fibers is very different in vascular tissue, however. 

Intermolecular - properties utilizing the ability of proteins to form junctions of its own molecules to themselves or to other components including viscosity, thickening, gelation, film formation, foaming, fiber formation, adhesion, cohesion, stickiness, hardness, complex formation, spreading, elasticity, and plasticity. 

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... 

It is probable that Bailey s first interest in the muscle field, in which lies his greatest contribution, was aroused by the work of Astbury and Dickinson who showed that fibers of denatured myosin behaved in ways similar to keratin so far as their elastic properties were concerned and their structures were revealed by X-ray analysis. At this time the Chibnall group was much interested in the amino acid composition of proteins. The obvious similarities in fibrous behavior between keratin and myosin despite their differences in amino acid composition, particularly in cystine content, stimulated Bailey to make a comparative study of the composition of some of the then recognized muscle proteins. This was Bailey s first paper on muscle and extension of the... 

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