Al tra sform ion n a 24 possible to generate with

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Unformatted text preview: y p strct ud 38). I s o 110 a rs p 140 s raw on diameter and tensile strength sug- has been reported positively correlated rediuctere (sizen c( ntrast, spidend roduce silkkD) (Fig. 2A, s that it should be). Several groups have attempted to spin in an as r ult o ap Fig. al tra sform ion n a (24 possible to generate with molecular orientation, resulting lanesa3esandf r4;id physic2B, nlaneat2) iproduced from 472 precipitated similarly couldJANUARY e redissolved SCIENCE www.sciencemag.org 18 only b 2002 VOL 295 s similar to native dragline silk with increase in the proportion of the -sheet cryssingle processing step in parallel with drawing in strong denaturing solvents such as hexaflusilk protein fibers artificially. Most efforts (36concatemers iofintheaw is precludgene 7(ADF-33 and talline areas and amorphous domains , because postsp nn g dr ADF-3 ed (7, 3 , 37). A transition of oroisopropanol or guanidine hydrochloride (23). have involved wet spinning ADF-3birefringence was shown 39a)r. prhecessindneisig npaeamlteitngsinllfof rfMaSpI, respectiveof reconstituted fibers ul T o sp and ar su er a obe oora mtoon ADF-333) n g r dimer i w f r ma i dB between the His and ADF-3 This differencTheolubility may be attributed to e in s secretory pathway Bombyx mori (25–27 ) orBnative ADF-3 Hissilk were diversall stinstances,ommon different expression spider fibers producedtiinwcultured acells Bioengineering:6,synthetic silks ly. In ity ar ng ith a c the prim ry silk (Fig. and D). brittle, fibers demonstrated protei sequen . I i at a by va ythe presence of the COOH-terminus in ADF-3 (28, 29). Recombinant whereas proteins have silk ADF-3 properties. vectorsneusedciematrys saenqtiuceinceesd atnsecretion of soluble enabledpthe hdt spinnirng appreciable mechanical ing th silk pr and MaSpII rc– spider silk proteins produced in been spun with harshers solventsicrosuchallyaster mesilkparameters, fibers the a range of Distinct spider silk proteins in with media. specificaFib observed m scopic af chanical testing were generally uniform with tions can be 37). Recombinant DNA (30) as diluents or dimammalian cells, suggesting that the more hyhexafluoroisopropanoltinconstruct: ngation. These elongateproteins withproduced (of applications: for 120, 150, molecularThese fibers sizes of dis ct areas of elo d could be used in a variety cytoplasm a as concentrated ter decre d example, and fine kD have sutures drophilic COOH-terminal 100 amino acids [ablute D protein solutionsrein showed a 12% diameformicase an190, 250, as very750 monofilament been found in the 26 protein folding endoplasmic reticulum (ER) glycosylation formation of disul de (—S-S—) bonds between pairs of cysteine residues quality control (veri cation of folding) packaging into vesicles for transport to Golgi cytoplasm Fig. 7. Scanning electron micrographs of an ADF-3 as-spun fiber. (A) Analysis of fiber surface (magnification, 500); (B) analysis at a break point to examine the fiber interior core ( 2000). www.sciencemag.org SCIENCE VOL 295 18 JA...
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