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Spider silk
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RachelBoyd (Talk | contribs) (New page: '''''Spider Silk''''' {| |Spider silk is comparable in strength to carbon fibres |- |Highly structured at the nanometre scale – not good for synthetic materials |- |Repetitive structur...) |
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|''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. | |''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. | ||
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| + | | '''Fahnestock et al 2000''' | ||
Revision as of 14:07, 30 May 2010
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 et al 2000 |
