A convenient assay method for the quality control of peptides and proteins

The development of a convenient and very accurate procedure with which to discriminate among subsets of structurally similar peptides and proteins, and measure enantiomeric purities with very good accuracy, has been described in a series of recent articles. A factor preventing its general application to all peptide forms is that comparisons were originally limited to closed subsets of structurally similar types, e.g., dipeptides, tripeptides, and insulin drug forms. In the most recent of these articles, a modification to the method was described which did enable the comparisons to be extended between sets, in particular the di-and tripeptides. That same modification is extended even further in this article to include additional di- and tripeptides, glycylglycine oligomers, insulin drug forms, and neuropeptides. The same principal component analysis treatment used for data reduction and statistical comparisons in prior work enables the discrimination among 49 of the total of 51 analytes investigated.