Chiral Technologies sell column that can separate all of the D/L amino acid
mixtures.
If you want to trace racemization during the synthesis, you may need to
hydrolyze peptide with minimum racemization and compare with the standard
mixture of the protected amino acids used for your synthesis that was
subjected to similar hydrolysis conditions.
Michael Breslav
R.W.Johnson PRI
Spring House, PA
> > I have been spending a good deal of deal trying to get an universal
> > procedure,and I
> > found out that no matter which method I tried,it does not work all the
> > time.
> > If the method is relatively small,and I will not be pinned down on
> size,a
> > reverse phase HPLC separation will do the job.If you can get same
> > column,conditions,etc.as the initial
> > run,it should work when combined with amino acid analysis.Once,I got a
> > peptide which gave
> > baseline resolution of two peaks of identical size.I found out that the
> > researcher
> > synthesized the derivatives,using the D,L-amino acid.
> > To prove the amount of D-amino acid is not so easy.I have seen
> > publications,and I tried
> > the procedures.They work for only a few amino acids.Probably,the best
> > method is that of
> > N.Nimura and T.Kinoshita,J.Chromat.,vol.352,169-177(1986).It relies on
> the
> > reaction of
> > primary amino acids with 0-phtaldehyde(OPA),in presence of sulfur
> compound
> > which is usually
> > the L-form.A ternary compound is formed,and it is possible to separate a
> > complex with
> > L-amino acid from D-amino acid,by the fact that there is a L-L and D-L
> > form.The authors and
> > Ihave been using N-acetyl-L-cysteine,although other sulfur compounds
> have
> > been used.
> > It is a precolumn derivatization and detection is fluorometric.I do not
> > think that any
> > other physico-chemical method will work.
>
>
> Vladimir Titov
>
> Bokiron Ltd., Moscow, Russia
>
> vmtitov@aha.ru
>
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