AMBER Archive (2005)

Subject: Re: AMBER: D-enantiomers

From: FyD (fyd_at_u-picardie.fr)
Date: Thu Sep 22 2005 - 02:03:55 CDT

Quoting Peter Gannett <pgannett_at_hsc.wvu.edu>:

> I don't see why charges would change. For optical isomers, the only
> difference is suppose to be the rotation of plane polarized light. It
> is true that as soon as you link them together, you'll get diastereomers
> but even with this, I don't see why atom charges would change.

For enantiomers, the charges 'should' be the same, Yes.
For diastereosimers, my understanding is that they 'should' be _different_.
The question is "how much" ?

For instance, "RR" & "RS" Threonine are dia.: They are in fact two different
'products' (They have different NMR, HPLC spectra etc...).
Consequently, they should have different charges also...
(Moreover, it is very unlikely that the global minimum of each of these dia.
would be the same)

Similarly, I would guess the same 'problem' for D-ALA-L-ALA & L-ALA-L-ALA.
(I am sure you can differentiate these 2 'peptides' by HPLC..).

Regards, Francois

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