Spider silk

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(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