Determination of glyoxylyl-peptide concentration using oxime chemistry and RP-HPLC analysis

Glyoxylyl-peptides are useful peptide derivatives in the context of hydrazone, oxime or thiazolidine ligations. We describe a method for the determination of glyoxylyl-peptide concentration based on the reaction of the alpha-oxo aldehyde group with an excess of O-benzylhydroxylamine. The amount of O-benzylhydroxylamine necessary to convert the alpha-oxo aldehyde group into the corresponding O-benzyloxime was determined by RP-HPLC analysis and corresponded to the quantity of glyoxylyl-peptide used in the experiment. The method is rapid, sensitive, accurate and allows the automated analysis of several samples.