racemisation
Auspepstaff (auspepstaff@c031.aone.net.au)
Thu, 30 Sep 1999 14:57:41 +1000 (EST)
Dear ABRFers,
I have a synthetic problem that I don,t understand.
I have made a peptide with a C-terminal GlyOL group. I did this by making
BocGlyOL succinate, linkng this to MBHA resin and making the peptide by Boc
chemistry. The peptide was HF cleaved yielding the peptide succinate as a
clean looking single peak by RP HPLC with the expected MW. Saponification of
the succinate from the C-terminus proceeded smoothly yielding the peptide
product with the correct MW but the RP HPLC trace was broad suggesting two
closely eluting peaks. By finding an isocratic condition to monitor the
crude peptide two product peaks were resolved explaining the broad peak seen
initially. My problem is that with no chiral centres on the GlyOL how can
the saponification reaction cause racemisation? There is N-Me Phe two
residues from the GlyOL and I am wondering whether this is the residue
responsible for the two peaks. I welcome any suggestions
Denis Scanlon
Auspep P/L