Algorithms for the quantitative validation of chiral properties of peptides

Complexation with Cu(II) ion in strong aqueous base, combined with visible range circular dichroism detection, were used to quantitatively differentiate among the L-enantiomers of the GG, GA, GY, AG, AA, AY, YG, YA, and YY dipeptides and the D-enantiomer of GA. Using ellipticity data at all (n = 1500) wavelengths in the measured spectra, and two novel data reduction procedures, quantitative determinations were made of the compositions of binary mixtures. For mixtures made with the L-GA and D-GA enantiomers, the accuracy of the measured enantiomeric purities was better than 0.17 % over the 1-48 % range for the minor component. The method has considerable potential for use in quality control of peptide and protein biotechnological drug forms.