Natural fibrous proteins

Inoue, S., Tsuda, H., Tanaka, T., Kobayashi, M., Magoshi, Y., and Magoshi, J. (2003). Nanostructure of natural fibrous protein In vitro nanofabric formation of Sarnia cynthia ricini wild silk fibroin by self-assembling. Nano Lett. 3, 1329-1332. 

Collagen is a natural fibrous protein found in human cartilage, connective tissue, and bone. Glutaraldehyde cross-linked bovine collagen is a sterile, biocompatible, biodegradable, purified bovine dermocollagen cross-linked with glutaraldehyde, mixed in a phosphate-buffered saline solution. 

Conformational study of natural fibrous proteins and their model polypeptides by H CRAMPS NMR... 

Next, we describe the application to the structural analysis of natural fibrous proteins in the solid state based on H chemical shifts, mainly of the H" signal of the model polypeptides. 

Some natural fibrous proteins and sequential model polypeptides have been used as follows (1) Tussah Antheraea perni silk fibroin [a-helix form], (2) Bombyx mori silk fibroin [silk I and II forms], (3) poly(L-alanyL-glycine) [Ala-Gly]i2 [silk I and II], (4) collagen fibril [triple-strand helix], and (5) poly(L-prolyl-L-alanyL-glycine) [Pro-Ala-Gly [triple-strand helix]. 

Table 4. Synthetic conditions, conformational characteristics, and H and chemical shifts of natural fibrous proteins and their model polypeptide samples (from refs 64 and 67)...

CAS 68238-35-7 EINECS/ELINCS 269-409-1 Synonyms Animal keratin Detoxin Definition Natural fibrous protein derived from hair, wool, horn, nails, epidermis, etc. in animals Properties Insol. in org. soivs. absorbs and holds water dens. 1.00 amphoteric Toxicology LD50 (IV, rat) 45 mg/kg may cause acute pulmonary edema TSCA listed Uses Biological additive, hair conditioner, skin conditioner in cosmetics in foam-type extinguishers prod, of protein hydrolysates coating enteric pills not affected in stomach but dissolved by alkaline intestinal secretions organic filler... 

Fibrous proteins, although interesting for their structural properties, represent only a small percentage of the proteins found in nature. Globular proteins, so named for their approximately spherical shape, are far more numerous. 

Fibrous protein (Section 26.9) A protein that consists of polypeptide chains arranged side by side in long threads. Such proteins are tough, insoluble in water, and used in nature for structural materials such as hair, hooves, and fingernails. 

The natural polymers known as proteins make up about 15% by mass of our bodies. They serve many functions. Fibrous proteins are the main components of hair, muscle, and skin. Other proteins found in body fluids transport oxygen, fats, and other substances needed for metabolism. Still others, such as insulin and vasopressin, are hormones. Enzymes, which catalyze reactions in the body, are chiefly protein. 

Naturally, very long T,c values are expected for solids as viewed from the expected correlation time at the low temperature side of the T c minimum (0.1-0.2 s) as shown in Figure 1. Indeed, their values turns out to be the order of 10-30 s for carbon sites in the absence of internal fluctuations as in polysaccharides such as (1 — 3)-p-D-glucan and (1 —> 3)-p-D-xylan,46 8 fibrous proteins such as collagen49 and silk fibroin,50 free and metal-complexed ionophores,51 or in some instances up to 1000 s as in crystalline polyethylene.52... 

Elucidation of the three-dimensional structures of / -structural fibrous proteins has attracted the interest of scientists for more than 50 years. In the early days, the objects of these studies were predominandy the naturally occurring fibrous assemblies obtained from jS-silk and stretched mammalian... 

Papanikolopoulou, K., Schoehn, G., Forge, V., Forsyth, V. T., Riekel, C., Hernandez, J.-F., Ruigrok, W. H., and Mitraki, A. (2005). Amyloid fibril formation from sequences of a natural jS-structured fibrous protein, the adenovirus fiber. J. Biol. Chem. 280, 2481-2490. 

The nature of the amino acid residues is of prime importance in the development and maintenance of protein structure. Polypeptide chains composed of simple aliphatic amino acids tend to form helices more readily than do those involving many different amino acids. Sections of a polypeptide chain which are mainly non-polar and hydrophobic tend to be buried in the interior of the molecule away from the interface with water, whereas the polar amino acid residues usually lie on the exterior of a globular protein. The folded polypeptide chain is further stabilized by the presence of disulphide bonds, which are produced by the oxidation of two cysteine residues. Such covalent bonds are extremely important in maintaining protein structure, both internally in the globular proteins and externally in the bonding between adjacent chains in the fibrous proteins. 

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