Biological macromolecules fibrous proteins

Fibrinogen is a fibrous protein that was first classified with keratin, myosin, and epidermin based on its 5.1 A repeat in wide-angle X-ray diffraction patterns (Bailey et al., 1943), which was later discovered to be associated with the Q-helical coiled-coil structure. It is a glycoprotein normally present in human blood plasma at a concentration of about 2.5 g/L and is essential for hemostasis, wound healing, inflammation, angiogenesis, and other biological functions. It is a soluble macromolecule, but forms a clot or insoluble gel on conversion to fibrin by the action of the... 

Biological macromolecules such as polysaccharides, fibrous or membrane proteins characteristically adopt a unique secondary structure which may be related to a variety of physical or biological properties. Elucidation of the three-dimensional structure of these systems is not always straightforward, because, in many instances, they are insoluble in ordinary solvent systems, and crystallization for X-ray diffraction study is extremely difficult. A possible disruption of a particular secondary structure should also be anticipated, when they are solublized in a solvent or detergent. Therefore it is essential to clarify their secondary structures either in the solid, gel or membrane-bound state without any attempt at solubilization. 

Different kinds of preferred orientations can also be developed with crystalline polymers. The native state of many macromolecules of biological interest, such as the fibrous proteins, is characterized by a preferred crystalline orientation. Similar conditions can also be obtained in other polymers by deformation of the specimen... 

The melting-crystallization of naturally occurring macromolecules of biological interest can also be analyzed within the framework that has been developed here. A good example is found in the behavior of the fibrous protein collagen. Present in major proportions of the repeating units in the collagen molecule are the... 

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