Spider silk
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|'''''Spider Silk''''' | |'''''Spider Silk''''' | ||
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|Spider silk is comparable in strength to carbon fibres | |Spider silk is comparable in strength to carbon fibres |
Revision as of 14:21, 30 May 2010
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Spider Silk |
Spider silk is comparable in strength to carbon fibres |
Highly structured at the nanometre scale – not good for synthetic materials |
Repetitive structures- GXG motif |
Glycine rich segments – hard and soft segments alternating |
Hard= hydrogen bonding cross-linked crystallites (polyalanine) forming an amorphic beta sheet structure, |
Soft= flexibility (Glycine rich) |
Major protein from Nephila clavipes – MaSP1 tandem variants of |
A GQG GYG GLG SQG A GRG GLG GQG A GA6GGx |
MaSP2 also has a repetitive structure – difference soft segment contains proline containing pentamers: The consensus repeat is _GPGGY GPGQQ.3GPSGPGS A8. Similar structure to Elastin – elastic properties of drag-line by the folding of pentamer structure. |
In the spider – silk in 3 phases |
1) Extremely viscous (withstand shear forces inside spider), |
2) Liquid crystallite lower viscosity (near exit duct/glycine rich may be involved), |
3) Insoluble fibre (result of dehydration and drawing). |
MaSP1 and MaSP2 – Drag line |
MaSP1-Auxilary |
MaSP2- Glue silk only |
Neither- Cocoon silk |
Super contraction associated with pentamer motif when wet: low visco-elasticity |
Mimic natural proteins or simplify – Mimic structural significance still uncertain for some sequences |
DPB1- Optimised for B.subtilis |
B.subtilis potential host as simple secretion system compared to yeast. Secretion has advantages over expression in E.coli however; insufficient proportion of protein was secreted by yeast. |
Fahnestock, S. R., Yao, Z., & Bedzyk, L. a. (2000). Microbial production of spider silk proteins. Journal of biotechnology, 74(2), 105-19. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11763501. |