Elastin water

It is the purpose of the present work to collect reliable volumetric data on the system elastin-water and to compare them with the scarce literature data on similar natural polymer systems or on synthetic polymeric systems. The measurements have been purposely limited to the region of low water contents where the system can be considered homogeneous. 

The data for the system polycarbonate-dibutyl phthalate, which are included in Figure 4 for the sake of comparison, show a behavior similar to that described for the elastin-water system. The datum for the most highly plasticized sample (DBF content 20%), which at the measurement temperature (25"C) is probably very near the onset of the glass transition, seems to indicate a less effective volume contraction than at lower plasticizer content. 

Elastins Water, ethylene glycol, di-, tri- and tetra-ethylene glycol D [168]... 

Chemical Composition. From the point of view of leathermaking, hides consist of four broad classes of proteins coUagen, elastin, albumen, and keratin (3). The fats are triglycerides and mixed esters. The hides as received in a taimery contain water and a curing agent. Salt-cured cattie hides contain 40—50% water and 10—20% ordinary salt, NaCl. Surface dirt is usuaUy about 2—5 wt %. Cattie hides have 5—15% fats depending on the breed and source. The balance of the hide is protein (1). 

Airway cross-sections have the nominal anatomy shown in Fig. 5.16. Airway surface liquid (AST), primarily composed of mucus gel and water, surrounds the airway lumen with a thickness thought to vary from 5 to 10 mm. AST lies on the apical surface of airway epithelial cells (mostly columnar ciliated epithelium). This layer of cells, roughly two to three cells thick in proximal airways and eventually thinning to a single cell thickness in distal airways, rests along a basement membrane on its basal surface. Connective tissue (collagen fibers, basement membranes, elastin, and water) lies between the basement membrane and airway smooth muscle. Edema occurs when the volume of water within the connective tissue increases considerably. Interspersed within the smooth muscle are respiratory supply vessels (capillaries, arteriovenous anastomoses), nerves, and lymphatic vessels. 

TLC. Aliquots of samples and standards were run on silica-coated thin layer chromatography (TLC) plates in either n-butanol/acetic acid/water (4 1 1 by vol. (BUOH/HAC/H2O)) or n-propanol/concentrated ammo-nia/water (8 1 11, pre-equilibration). These eluents were previously described (Keller et ah, 1984) for the two-dimensional TLC-separation of elastin cross-links. 

In contrast to milk, where samples are primarily derived from cows, meat analysis has to be performed in samples of a widely different animal origin including cattle, lamb, swine, poultry, and fish. Muscle is a complex matrix with a pH of 5.7, composed of muscle fibers, various types of connective tissue, adipose tissue, cartilage, and bones. Sarcoplasmic proteins such as myoglobin, and glycolytic enzymes are soluble in water while the myofibrillar proteins such as myosin and actin are soluble in concentrated salt solutions (14). The connective tissue proteins, collagen and elastin, are insoluble in both solvents. 

Dynamic mechanical response spectra of elastin145 (insoluble protein of vessels and ligaments), poly(ethylene terephthalate)141 and polycarbonate based on Bisphenol A (4,4 -dihydroxydiphenylmethane)141 show that incorporated water brings about enlargement of the existing secondary loss peak and its displacement toward lower temperatures. In conformity with the latter result, the activation energy of the relaxation process of elastin decreases. So far, no detailed data on this type of relaxation have been collected so that the copartidpation of water in the molecular motion cannot be specified more accurately. 

Fibrous proteins - these have linear molecules, are insoluble in water and resistant to alkalis and acids. Collagen (in tendons and muscles), keratin (in nails, hair, horn and feathers) and elastin (in arteries) are all fibrous proteins. 

The azo-modified, elastin-like polypeptide XIV illustrated in Scheme 9 exhibits a so-called inverse temperature transition" that is, the compound gives cross-linked gels that remain swollen in water at temperature below 25 °C but deswell and contract upon a rise of temperature. The trans-cis photoisomerization of the azo units, obtained through alternating irradiation at 350 and 450 nm, permits photomodulation of the inverse temperature transition.[S9] The result indicates that attachment of a small proportion of azobenzene chromophores is sufficient to render inverse temperature transition of elastin-like polypeptides photoresponsive, and provides a route to protein-based polymeric materials capable of photomechanical transduction. 

Elastin is not a true rubber as it is not self-lubricating. It has elastic properties only in the presence of water. At rest, elastin is tightly folded, stabilized by hydrophobic interactions between nonpolar residues this has been termed an oiled coil. On stretching, these hydrophobic interactions are broken, and the nonpolar residues are exposed to water. This conformation is thermodynamically unstable, and once the stretching force is removed, the elastin recoils to its resting state. 

Scleroproteins. Insoluble in water and neutral solvents and resistant to enzymic hydrolysis. These are fibrous proteins serving structural and binding purposes. Collagen of muscle tissue is included in this group, as is gelatin, which is derived from it. Other examples include elastin, a component of tendons, and keratin, a component of hair and hoofs. 

Enzymes, such as creatine kinase, have been grafted on to collagen films by using water soluble carbodiimides. Porcine intestinal collagen has been crosslinked with EDC in acetone to provide a remodelable scaffold. EDC crosslinking of collagen/elastin matrices is also used to prepare fiat scaffolds. ... 

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