What type of structure is spider silk?
Silk is a composite material with a hierarchical structure. Its primary structure, the amino acid sequence, has been optimized over millions of years of biological evolution (12). Spider dragline silk is thought to be composed mainly of two proteins, Spidroin I and II (13, 14).
What is the chemical compound for spider web?
Spider silk is a protein fiber. Major amino acids in the silk proteins are alanine and glycine. Serine and praline are also present in significant quantities in some types of silk. Glycine-rich regions give spider silk its elasticity, forming amorphous areas in its structure.
Is silk alpha helix?
The hydrogen bonds in the silk form beta pleated sheets rather than alpha helixes because of where the bonds occur. The hydrogen bonds go from the amide hydrogens on one protein chain to the corresponding carbonyl oxygen across the way on the other protein chain.
What is the function of spider silk?
Spider silk is a protein fibre spun by spiders. Spiders use their silk to make webs or other structures, which function as sticky nets to catch other animals, or as nests or cocoons to protect their offspring, or to wrap up prey.
What is the chemical structure of silk?
Silk fibers are composed of fibroin microfibrils assembled into filaments. Silk fibers consist of two fibroin filaments each produced by one of the worm’s salivary glands during spinning. Both filaments are then covered by sericin, an adhesive and hydrophilic protein to form the structural unit (Poza et al., 2002).
What is the chemical formula of silk?
mori silk fibroin is composed of two protein chains, heavy-chain (H-fibroin) with the molecular weight of approximately 350 kDa and light chain (L-fibroin, Mw ~ 26 kDa) covalently linked by a disulfide bond at the carboxy-terminus of the two subunits [23-25] (Figure 3a).
How does a dragline work?
A large excavator uses a dragline to pull a bucket by a wire cable. The operator lowers the bucket down to material that is supposed to be excavated. The operator than draws the cable so that the bucket gets dragged along the ground surface and digs into the material.
What is the working range of a dragline?
The length of the boom ranges from 45 to 100 metres (148 to 328 ft). In a single cycle, it can move up to 450 tonnes of material.