Silk fibroin sericin from

Isolation. The best natural source of alanine is silk which contuna nearly 25% of this amino acid. Other proteins contain less than 10% of alanine. Alanine may be readily isolated by the classical ester procedure of Emil Fischer (280) which has been applied to silk, silk fibroin, sericin, casein, gelatin, and other proteins. Glutamic acid hydrochloride is crystallized from the protein hydrolysate, the remaining amino acids are esterified and glycine ethyl ester hydrochloride is precipitated. The free amino acid esters are fractionally distilled in vacuo and the fraction containing alanine ethyl ester (b. p. about 50 C./10 mm.) is hydrolyzed. The yield (308) of nearly analytically pure n-alanine (225) is about 50 g. (20%) from 250 g. of silk fibroin. 

Cells of the silk gland from B. mori silkworm synthesize an enormous quantity of silk proteins, fibroin and sericin, during a brief period in larval development without cell division. Silk fibroin is exclusively synthesized in the posterior silk gland (each cell produces 10 fibroin molecules, for example, about 80 mg during a period of only 3 to 4 days fifth instar larva)... 

Moth larvae produce the polymeric material from a liquid crystalline phase to form a protective cocoon silk is extruded from the spinneret as a bave , consisting of two roughly triangular fibroin filaments ( brins ), about 20 pm across, bound together by a second protein, sericin (Figure 13). In commercial production, the chrysalid is killed before it can hatch (which would damage the thread), and a continuous filament can then be unreeled from each cocoon, giving typically 500-800 m of useable thread. 

Fibroin—Sericin—is obtained from silk by removal of fat, albumin, coloring matters, etc., by the proper solvents. It dissolves, like cellulose, in ammonio-sulfate of copper solution. It does not contain S, and resembles gelatin in its chemical composition. 

Silk, or more precisely, natural silk, is produced by certain worms, caterpillars, and moths. The most important product is the high-quality silk that comes from the mulberry silk moth Bombyx mori Linne) the larvae use it to enclose themselves in a coccoon, which consists of 78% silk fibroin and 22 % silk glue (sericin). 

Silk fibroin solution was obtained from the posterior part of the middle division of the silk gland in full-grown larvae (1 day before spinning) of Bombyx mori. The sericin was removed by washing with deionized water [21-23]. 

Silk fibroin is a fibrous protein obtained by the larvae of Bombyx mori, other moth genera such as Antheraea, Cricula, and many other insects. The silk protein obtained from spiders and silk worms produces the toughest and strongest fibres [115]. Silkworms produce silk whose main components are fibroin and sericin amongst which fibroin constitutes the core of silk, and sericin is glue like protein surrounding the core. Fibroin is composed of various... 

Silk (qv) suture is made from the threads spun by the silkworm Bombjx mori. The fiber is composed principally of the protein fibroin and has a natural coating composed of sericin gum. The gum is usually removed before braiding the silk yams to make sutures in a range of sizes. Fine silk sutures may be made by simply twisting the gum-coated silk yams to produce the desired diameter. White silk is undyed. Silk is either dyed black with logwood extract or blue with D C Blue No. 9. The suture may be uncoated or coated either with high molecular weight polydimethylsiloxane or with wax. 

Silk fibers or monolayers of silk proteins have a number of potential biomedical applications. Biocompatibility tests have been carried out with scaffolds of fibers or solubilized silk proteins from the silkworm Bombyx mori (for review see Ref. [38]). Some biocompatibility problems have been reported, but this was probably due to contamination with residual sericin. More recent studies with well-defined silkworm silk fibers and films suggest that the core fibroin fibers show in vivo and in vivo biocompatibility that is comparable to other biomaterials, such as polyactic acid and collagen. Altmann et al. [39] showed that a silk-fiber matrix obtained from properly processed natural silkworm fibers is a suitable material for the attachment, expansion and differentiation of adult human progenitor bone marrow stromal cells. Also, the direct inflammatory potential of silkworm silk was studied using an in vitro system [40]. The authors claimed that their silk fibers were mostly immunologically inert in short and long term culture with murine macrophage cells. 

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