A great model for a desalination membrane is any of the millions of cells we have in our bodies.

Last month NIH funded researchers at the University of Illinois at Urbana-Champaign and the University of Arizona modeled Aquaporins — a class of proteins that form membrane channels in cell walls. Aquaporins allow for water movement between a cell and its surroundings. Researchers found that the same protein can be used as a water channel or an ion channel depending on the signaling pathway activated in the cell.

So what?

If you had an ion gate that could ward off charged sodium ions depending on their charge then you might be able to put one of these gates on a semipermiable membrane and do some serious water desalination–just like human cells do!

The modeling work at Illinois and Arizona builds on models used for the study of ion channel gating kinetics at Los Alamos National Laboratory last year.

This week researchers learned a bit more about the shape of the gate:

Researchers decipher the shape of the sodium/potassium ion pump

Researchers decipher the shape of the sodium/potassium ion pump

Channel surfing. Charged oxygen atoms (red) deep inside a sodium/potassium pump are part of a filter that allows only ions with the correct charge to pass from one side of the cell’s membrane to the other.

Two new papers from Rockefeller University professor David Gadsby, head of the Laboratory of Cardiac and Membrane Physiology, go a long way toward describing the shape of the gated channel in the Na/K pump and providing an understanding of how this pump — and others like it — collects ions on one side and releases them on the other.Many of the residues in an ion pump have an electrical charge that works to either draw in or repel approaching ions, allowing only those with the correct charge to flow through to their destination.

As I mentioned this looks a good model for desalination with carbon nanotubes –if the nanotubes were so large they required gating. Manifest Interconductance Rank (MIR) models and models called Aggregated Markov Processes used for ion gating studies at Los Alamos……. might be adapted for water desalination studies.

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