Properties of collagen, physical

The structure and physical properties of collagen are well known. Several recent reviews are available to interested readers (3, 4, 5, 6, 7,8). Some of the work pertinent to the problems of using collagen as a biomaterial along with some of our recent work on reconstituting collagen surfaces are reviewed here. 

For a better understanding of the relation of structural and physical properties of collagen sponges and their biological reactivity, it is necessary to explain in more detail the processing methods of the raw material. 

The chemical and physical properties of collagen proteins are different in tissues such as skin, swim bladder, and the myocommata muscle. In general, collagen fibrils form a delicate network structure with varying complexity in the different connective tissues in a pattern similar to that found in mammals. However, the collagen in fish is much more thermolabile and contains fewer, but more labile, cross-links than collagen from the warm-blooded vertebrates. 

Rich H, et al. Effects of photochemical riboflavin-mediated crosslinks on the physical properties of collagen constmcts and fibrils. J Mater Sci Mater Med 2014 25(1) 11—21. 

H. Rich, M. Odlyha, U. Cheema, V. Mudera, and L. Bozec, Effects of photochemical riboflavin-mediated crosshnks on the physical properties of collagen constructs and fibrils, /. Mater. Sci. Mater. Med., 25 (1), 11-21, 2014. 

Collagen, the major component of most connective tissues, constimtes approximately 25% of the protein of mammals. It provides an extracellular framework for all metazoan animals and exists in virmally every animal tissue. At least 19 distinct types of collagen made up of 30 distinct polypeptide chains (each encoded by a separate gene) have been identified in human tissues. Although several of these are present only in small proportions, they may play important roles in determining the physical properties of specific tissues. In addition, a number of proteins (eg, the Clq component of the complement system, pulmonary surfactant proteins SP-A and SP-D) that are not classified as collagens have... 

Ikoma, T., Kobayashi, H., Tanaka, J., Walsh, D., and Mann, S. (2003). Physical properties of type I collagen extracted from fish scales of Pagrus major and Oreochromis niloticas. Int.. Biol. Macromol. 32, 199-204. 

Inouye, K., Kobayashi, Y., Kyogoku, Y., Kishida, Y., Sakakibara, S., and Prockop, D. J. (1982). Synthesis and physical properties of (Hydroxyproline-Proline-Glycine)10 Hydroxyproline in the X-position decreases the melting temperature of the collagen triple helix. Arch. Biochem. Biophys. 219, 198-203. 

The size and shape of a macromolecule can be determined by measuring the physical properties of isolated macromolecules in solution. Large rigid macromolecules that are derived from extended structures including the collagen triple helix result in rodlike rigid or semirigid structures. The size, shape, and physical parameters for macromolecules discussed in this book... 

Collagen s promotion of wound healing has also been reported for many years. Collagen protein is a natural biopolymer that In isolated and purified form is extraordinarily suitable for biomedical applications. The physical, physicochemical, and biological properties of collagen make it an interesting component for so-called active wound dressings. 

Basically, there are three major groups of proteins in muscle tissue (a) the sarcoplasmic proteins of the muscle cell cytoplasm, (b) the myofibrillar proteins, soluble at high ionic strengths, that make up the myofibril or contractile part of the muscle, and (c) the stromal proteins comprised largely of the connective tissue proteins, collagen, and elastin. The myofibrillar proteins and the stromal proteins are fibrous and elongated they form viscous solutions with large shear resistance. These properties coupled with other lines of indirect evidence indicate that the physical properties of the myofibrillar and stromal proteins are directly related to the texture and tenderness of meat (34). 

One of the important requisites for such study, however, is an ability to follow the actual behavior of individual fibrils and protofibrils. Physical methods, such as electron optics and X-ray diffraction, are particularly useful in this regard, as has been amply demonstrated in preceding sections. It is highly desirable that these methods, which reduce the size range over which extrapolation must be made to link the macroscopic phenomena with the molecular, be more widely used in connection with observations of the colloidal properties of collagen, such as swelling. While collagen offers favorable material for this extrapolation, experience of the past has shown that it must still be made cautiously in order to avoid mistaken conceptions. 

Stanley (1983) concluded that postmortem events influence the physical properties of meat, not only through rigor mortis, but also as a result of the action of numerous endogenous enzymes on myofibrillar structure, and perhaps, connective tissue as well. A major structural alteration that has been observed in postmortem muscle is Z-disc degradation. The unreactive chemical nature of collagen may preclude any major attack by endogenous muscle enzymes on this fibrous protein (Offer et al, 1988). 

The smaller proteoglycans include decorin, biglycan and fibromodulin. They have shorter protein cores and fewer GAG chains than their larger counterparts. Unlike aggregans, these molecules do not affect physical properties of the tissue, but are thought to play a role in cell function and organization of the collagen matrix [64]. 

Tangsadthakun, C., Kanokpanont, S., Sanchavanakit, N., Pichyangkura, R., Banaprasert, T, Tabata, Y, Damrongsakkul, S. (2007). The influence of molecular weight of chito-san on the physical and biological properties of collagen/chitosan scaffolds. JB o iater Sci, Polym 18, 147-163. 

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