Composition Of Silk Research Articles

ジョロウグモの引き糸と横糸の構造と変形

In the previous papers it was shown that the mechanical properties of spider threads taken from Nephila clavata called Jorougumo in Japan were excellent and thus the threads were expected to be one of the most useful materials in future, if produced in large quantities. In this paper, the analyses of composition and crystalline structure of dragline silk and the deformation behavior of dragline and capture thread were investigated. The results are as follows: (1) glycine and alanine are the most abundant amino acids and occupy about 70% of the total amino acids, (2) the crystalline structure is orthorhombic and the dimensions of the unit cell are about a=1nm, b=0.9nm and c=0.7nm, (3) the load-strain curve for the capture thread is J-shaped and its fracture strain is more than 200%, and (4) a wonderful mechanism for the capture thread named as “windlass system” is reconfirmed.

Isolation of a clone encoding a second dragline silk fibroin. Nephila clavipes dragline silk is a two-protein fiber.

Spider dragline silk is a unique protein fiber possessing both high tensile strength and high elasticity. A partial cDNA clone for one dragline silk protein (Spidroin 1) was previously isolated. However, the predicted amino acid sequence could not account for the amino acid composition of dragline silk. We have isolated a partial cDNA clone for another dragline silk protein (Spidroin 2), demonstrating that dragline silk is composed of multiple proteins. The amino acid sequence exhibits an entirely different repetitive motif than Spidroin 1. Spidroin 2 is predicted to consist of linked beta-turns in proline-rich regions which alternate with beta-sheet regions composed of polyalanine segments. This structure for Spidroin 2 provides a model for dragline silk structure and function.

Spider mite webbing—III. Solubilization and amino acid composition of the silk protein

1. 1. Amino acid composition of silk (or webbing) produced by the carmine spider mite, Tetranychus cinnabarinus (Boisduval), was determined. It differs from most other arthropod silk proteins, but resembles mammalian prekeratin. 2. 2. Several solvents were applied in order to dissolve spider mite silk. In addition to strong acids and bases, only Soluene® and sodium hypochlorite dissolved this silk. The effect of sodium hypochlorite on the amino acid composition of spider mite silk was compared with its effect on elastin and chymotrypsin. 3. 3. Several possible cross-linking mechanisms of spider mite silk are discussed on the strength of experimental evidence. 4. 4. It is suggested that spider mite silk represents an evolutionary link between pseudoscorpion fibroin and the keratins.

Ultrastructure and Composition of Pseudoscorpion Silk

Ultrastructure and Composition of Pseudoscorpion Silk

Amino acid composition of silk from the pseudoscorpion Neobisium maritimum (Leach): A possible link between the silk fibroins and the keratins

1. 1. Silk from the nests of the marine pseudoscorpion Neobisium maritimum (Leach) has been analysed for amino acids. 2. 2. The composition is totally different from that typical of Lepidopteran and spider silk fibroins being low in non-polar and small amino acid residues and high in basic and acidic amino acids. 3. 3. The composition closely resembles that of mammalian prekeratin. 4. 4. It is suggested that pseudoscorpion silk may represent an evolutionary link between the silk fibroins and the keratins.

A four-strand coiled-coil model for some insect fibrous proteins

The pupae of Indian paper wasp, Ropalidia marginata, produce silk that covers the opening of each cells in their hives, which probably helps in thermoregulation and providing mechanical stability. In this study an attempt has been made to investigate the amino acid composition and protein structure of Indian wasp silk using bioinformatics and experimental tools. The amino acid analysis of the regenerated solubilized wasp silk revealed high alanine and serine content that increases the propensity of α-helical and random coil and/or β-sheet structure respectively. The Matrix Assisted Laser Desorption/Ionization-Time Of Flight/Time Of Flight based protein fingerprinting analysis of the regenerated solubilized wasp silk revealed its short-range sequences. The protein modeling studies indicated the presence of predominant coiled coil α-helical and random coil structure in the protein isolated from wasp hive caps, similar to previous reports from the Vespoidea family. Fourier transform infrared spectroscopic analysis and X-ray diffraction analysis of the native paper wasp cap revealed the presence of mix of coiled coil α-helix and β-sheet structure in outer regions; whereas inner region contains tannin/intermolecularly bonded hydroxyl groups of polyphenols. The present study is first report to generate valuable insights about the chemical composition and secondary structure prediction of Indian paper wasp silk and highlight on nature's novel modus operandi to engineer unique functional fibrous matrix.

Composition of Silk

IT is well known that the sericin component of silk is soluble in water, and the fibroin is soluble in certain acids and a variety of salt solutions. The latter can be dialysed to leave a solution of fibroin in water1,2, from which water-soluble films can be cast. Ambrose et al.1 have shown by infra-red methods that these are in the α-configuration, and that, on denaturation by alcohol or ammonium sulphate or by stretching, an incomplete conversion to the insoluble β-form occurs.