Fibroin protein

Shulha, H., Foo, C.W.P., Kaplan, D.L., and Tsukruk, V.V. "Unfolding the multi-length scale domain structure of silk fibroin protein"Polymer 47(16), 5821-5830 (2006). 

The fibroin proteins found in silk fibers consist of large regions of p-pleated sheets stacked one on top of another, (a) Explain why having a glycine at every other residue allows the p-pleated sheets to stack on top of each other, (b) Why are silk fibers insoluble in water ... 

According to the graph, what is significant about spider fibroin protein ... 

Spider fibroin protein is a much stronger material than a-keratin in wool. Violet would like to create a strong protein for... 

Not all of the fibroin protein is in / -sheets. As the amino acid composition in Figure 6.12 shows, fibroin contains small amounts of other, bulky amino acids like valine and tyrosine, which would not... 

Not all of the fibroin protein is in / -sheets. As the amino acid composition in Figure 6.12 shows, fibroin contains small amounts of other, bulky amino acids like valine and tyrosine, which would not fit into the structure shown. These are carried in compact folded regions that periodically interrupt the sheet segments, and they probably account for the amount of stretchiness that silk fibers have. In fact, different species of silkworms produce fibroins with different extents of such non - / -sheet structure and corresponding differences in elasticity. The overall fibroin structure is a beautiful example of a protein molecule that has evolved to perform a particular function — to provide a tough, yet flexible fiber for the silkworm s cocoon or the spider s web. 

Finally, structural studies of two well-known silk fibroin proteins, Bombyx mori and Sarnia cynthia ricini, have been reported. Solid state NMR methods, such as C 2D spin-diffusion NMR and REDOR were used in addition to the quantitative use of the conformation-dependent chemical shifts, measured by C CP MAS. 

All silks are extrusion spun into a protective cocoon before the larva undergoes metamorphosis. This cocoon consists of a continuous double strand of fibroin protein, conglutinated by the sericin protein, which acts as a binder to glue the threads into the cocoon shell. 

Hota, M.K., Bera, M.K., Kundu, B., Kundu, S.C., Maid, C.K., 2012. A natural sUk fibroin protein-based transparent bio-memristor. Adv. Funct. Mater. 22, 4493-4499. 

The fibroin protein consists of a heavy chain (350 kDa, fib-H) (Takei, 1987) and a light chain (26 kDa, fib-L) molecule (Tanaka et al., 1993), which are connected by a disulfide link between two cysteine amino acids in fib-H and fib-L to form a... 

Concentrated adds like phosphoric acid (Schurz, 1954 Ishizaka et al., 1989), trifluoroace-tic acid (Ha et al., 2005), fannic acid (Um et al., 2001,2003 Yao et al., 2004), and a mixture solvent system of phosphoric and formic acid (Ki et al., 2007) can he used to dissolve silk fibroin. The use of these concentrated acids results in good soluhiUty of fibroin but they have a huge disadvantage. Peptide bonds between amino adds get attacked during dissolu-tioD causing degradation of fibroin protein. 

In contrast to concentrated acids or chaotropic salt solutions, fluorinated solvents do not affect the regenerated silk fibroin protein structure (Fu et al., 2009). 

Clemens, M.W., Downey, S., Agullo, R, Lehfeldt, M.R., Kind, G.M., Palladino, H., Marshall, D., Jewell, M.L., Mathur, A.B., Bengtson, B.P., 2014. Clinical application of a silk fibroin protein biologic scaffold for abdominal wall fascial reinforcement. Plastic and Reconstructive Surgery. Global Open 2 (11), e246. 

From WAXS and SAED data of both ProNectin F lyophilized powder and sprayed fibrils, the current model indicates that ProNectin F crystallizes into a chain folded pleated sheet of beta strands (Anderson et a/. 1994). The strands are oriented antiparallel. The beta strands are not fully extended, but have a more compressed crankshaft conformation. This conformation agrees with the predicted conformation of unoriented silk fibroin protein, the Silk I structure (Lotz and Keith 1971). The crystal dimension in the c direction (along the peptide backbone) is consistent with a theoretical length of 11.6 nm for nine SEP blocks (54 amino acids) in this conformation. This predicts that the width of the ProNectin F tile is controlled at least in part by the number of amino acids in the silklike block domains. 

FIGURE 10.8 Primary stmcture of the repeated amino acid units in fibroin protein. (See insert for color representation of the figure.)... 

FIGURE 10.8 Primary structure of the repeated amino acid units in fibroin protein. 

Silkworm silk, the silk from the cocoon of B. mori contains at least two major fibroin proteins, light and heavy chains, 25 and 325 kDa, respectively. These core fibers are encased in a sericin coat, a family of gluelike proteins that holds two fibroin fibers together to form the composite fibers of the cocoon case to protect the growing worm. Silkworm cocoon silk production, known as sericulture, produces high yields as the larvae can be maintained in high densities. The core sequence repeats in the fibroin heavy chain from B. mori include alanine-glycine repeats with serine or tyrosine [334]. It has been widely used as biomedical sutures and in textile production. 

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