X-Message-Number: 20989
Date: Tue, 28 Jan 2003 09:30:17 -0500
From: Jeffrey Soreff <>
Subject: sorting rotor mechanisms

> From: 
> Date: Mon, 27 Jan 2003 12:50:30 EST
> Subject: Re: CryoNet#20980 nano MNT and on and on and on.
>> From: Henri Kluytmans <>
>> Subject: Nanotech / MNT
...
>> A rod in the center of the binding site will protrude when it's
>> part of the rim is located inside the reservoir and will
>> mechanically press the molecule out off the binding site.
>> (Of course this operation requires some energy.)

>This is mere sci-fi. It recall me these novels where someone board on an
>interstellar astronef as he/she would use  a car. Fond that in a pulp fiction
>is not very interesting, find a similar idea in something presented as
>science or technology is far worst.

In biochemistry this sort of mechanical actuation of unbinding events
is called "allosteric effects".  Quoth
http://stingray.bio.cmu.edu/~web/bc/Lec/Lec13/lec13.html


"Allosteric effects occur when the binding properties of a macromolecule change 
as a

   consequence of a second ligand binding to the macromolecule and altering its 
   affinity

   towards the first, or primary, ligand. There need not be a direct connection 
   between the

   two ligands (i.e. they may bind to opposite sides of the protein, or even to 
   different
   subunits)"

The binding of the first ligand _strains_ the protein, changing the
geometry of the other binding sites, which changes the affinity for
the other ligands.  Not only is it not sci-fi, but your own red
blood cells' binding isotherm for oxygen depends on this effect.

              Best wishes,
              -Jeff

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