What’s up with Silk (besides being a self-assembling protein)?

I guess that it’s not just for men’s ties and women’s scarves anymore.

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8 COMMENTS

  2. Curious about the self-assembly part. It must be step growth polymerization. The clue is at the 2:57 mark: "as the water evaporates"

  4. Race – i wouldn't have thought to do that with silk.

    Chickenlittle – I don't know precisely how it's done, but it's cool.

    Odie – Not just for kimonos anymore.

  5. Chickie, wiki says that the main component of fibroin forms beta sheets that align with one another by hydrogen bonding, (I'm not sure if water disrupts this), but a second protein called sericin forms "the sticky material surrounding it". Perhaps evaporation leads to either degradation of the second protein or better coordination of the sheets of fibroin, but either way the amino acid components would have polymerized via the translation process. Post-translational processing may be where the trick lies, if there is any apart from facilitation of protein folding. But usually that term refers to covalent modifications, rather than the spatial orientation that is so important to coordinating proper protein structure (tertiary structure).

  6. Ritmo: He implies that they begin with monomers (amino acids). Even in nature, peptide bond formation is a dehydration condensation, catalyzed of course because it has too high of a kinetic barrier to be spontaneous.

    The formation mechanism catalyst(s) are likely proprietary–I'll bet I could get on the PTO website or even Google Patents and find it…
    _____________
    wv = covet. Thou shalt not!

  7. My apologies if I hadn't listened to the presentation carefully enough to realize he was synthesizing silk de novo, and not just modifying its processing following extraction from a natural source. You are of course right that the production of proteins from amino acid monomers constitutes polymerization, and that it does involve condensation.

    My understanding is that we've had the capacity for doing this artificially for a while, although most proteins complex enough for bio-therapeutic application are produced by bacteria rather than by more conventional synthesis. However, the building block of fibroin is a simple pentamer, so scaling the synthesis and polymerization of that should be easier than with something like insulin or erythropoietin.

    Of course, it's possible that his manufacturing process is biotechnological in nature as well.

  8. I guess when you brought up "self-assembly" I figured we'd have to be talking about tertiary structure. Pentameric fibroin peptides are too non-random in sequence (Gly-Ser-Gly-Ala-Gly-Ala) to leave their production to chance. Perhaps once he's got these pentamers formed already, though…

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