Tuesday, November 25, 2008

Protein folding, Nanotubes and Engineering

More on protein folding:
Many proteins have intricate folds and one of these fold types include the figure eight knot fold. A team of researchers tried to figure out how these proteins are folded. At present, it is only known that the knot is formed quickly soon after polypeptide chain formation, with an unknown mechanism. The researchers tentatively propose:
"an early threading event may be the defining feature of a polypeptide-knotting with the ensuing folding occurring in a similar fashion to unknotted proteins; the folding of a knotted protein differs only with an initial knotting event in a denatured-like state."

Perhaps an an as of yet undiscovered knot-folding machine?
Article: Exploring knotting mechanisms in protein folding


And nanotubes? Bah, old news... a few hundred million years old...
Tunnelling nanotubes: Life's secret network
Quote:
The closest animal equivalents to plasmodesmata were thought to be gap junctions, which are like hollow rivets joining the membranes of adjacent cells. A channel through the middle of each gap junction directly connects the cell interiors, but the channel is very narrow - just 0.5 to 2 nanometres wide - and so only allows ions and small molecules to pass from one cell to another.

Nanotubes are something different. They are 50 to 200 nanometres thick, which is more than wide enough to allow proteins to pass through. What's more, they can span distances of several cell diameters, wiggling around obstacles to connect the insides of two cells some distance apart. "This gives the organism a new way to communicate very selectively over long range," says Gerdes. It is a previously unknown way in which cells can communicate over a distance

Soon after they first saw nanotubes in rat cells, he and Rustom saw them forming between human kidney cells too. Using video microscopy, they watched adjacent cells reach out to each other with antenna-like projections, establish contact and then build the tubular connections. The connections were not just between pairs of cells. Cells can send out several nanotubes, forming an intricate and transient network of linked cells lasting anything from minutes to hours. Using fluorescent proteins, the team also discovered that relatively large cellular structures, or organelles, could move from one cell to another through the nanotubes
Quote:
Their work, published in May, shows that nanotubes are not just an artefact of the methods used to grow cells in culture, as some have suggested. And what they have seen is spectacular: some of the longest tunnelling nanotubes ever observed, more than 300 micrometres long, connecting dendritic cells in the cornea (The Journal of Immunology, vol 180, p 5779). "We can see them their whole course, spindling all the way through the cornea," says McMenamin. "It's fantastic."

"I'll bet you that within weeks to months, people will start noticing them in other tissues. It's just a case of how you look," he adds. "You've got to know what you are looking for. It's a bit like being a good bird-watcher. A hundred people will see a flock of seagulls, and it's only a very good bird-watcher who will spot this one tern flying in that flock."

Gerdes, meanwhile, continues to marvel at what is unravelling before his very eyes. "Whatever one can think of has been done by nature," he says. "It is unbelievable what the cell is able to do."
One striking feature that makes us different from other primates is our innate ability to develop a theory of mind at around 4-6 years. We start to develop the remarkable ability to simulate what other people are thinking and understand their thoughts through our own thinking. We also create our own model of the world in our own minds that leads to understanding of concepts.

Attempting to unravel nature's mysteries by trying to look at it from another engineering Mind's eye seems to make sense when one marvels at the engineering feats in cells. Why not?

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