wacky thought

Frank Fürst frank at fuerst.de
Mon Mar 15 07:09:41 EST 1999


Louis Hom wrote:
>         But my real question/idea is, I wonder if there's anything that we
> measure or postulate in proteins (say, CD or helix end-effects) that could
> actually be turned around to influence the behavior (folding, whatever) of
> the proteins.
It would have to be an essentially "qualitative" effect. CD is a
quantity, you get one molar ellipticity for alpha, an other for beta,
a third for irregular structure (at a certain wavelength in the far
UV). So if you apply something like the outcome of a CD-measurement,
i.e. you irradiate with circularly or elliptically polarized light, an
you do it with an energy (power/intensity) comparable to the
stabilization energy of a helix, you would at the same time influence
(and induce, thats at least what you seem to want) other secondary
structure, too. On the other hand, in this particular case and as I
think in most cases, the energy you would need (if one asumes it
works) would damage your macromolecule in an unspecific way.

So, if we found a macroscopic property that is connected with one
single microscopic property, we could start thinking if we can turn
the effect around. But I don't see anything.

And there's another reason why I'm sceptical. I didn't think it
through till the end. But in the Peltier effect, you get a
relationship between two macroscopic properties, temperature and
voltage. There's, of course, a microscopic chain of cause and effect,
but the phenomenon is macroscopic. So in what you actually do, you
don't have to think about quantum mechanics, energy levels (niveaus)
etc. But considering molecular properties of a protein, you do.
e.g. in fluorescence, you can see the polarity of the fluorophors
environment by the maximum emission wavelength. But the macroscopic
property you can play with is just intensity. Changing Excitation
wavelength will again just change the concentration of excited
molecules, and thats related to intensity. (And your macromolecule
clearly wouldn't bother about your changing the emission detection
wavelength, would it?)

Frank Fuerst, Institut für Biochemie der Uni Potsdam
Im Biotechnologiepark, 14943 Luckenwalde
Tel.: +49-3371-681334;   Fax.: +49-3371-681339
ffrank at rz.uni-potsdam.de
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