High-performance liquid chromatographic determination of sulfated peptides in human hemofiltrate using a radioactivity monitor

Abstract Specific labeling of tyrosine sulfate-containing peptides was achieved using a differential iodination approach. In a complex peptide mixture from human hemofiltrate, cold iodination to saturate free iodine binding sites was followed by mild acidic desulfation of tyrosine sulfate and subsequent radioiodination using iodine-125. Reaction steps were controlled by amino acid analysis using o -phthaldialdehyde precolumn derivatization and by spiking with a sulfated cholecystokinin fragment (CCK4-S). Separation of the peptide mixture with RP-HPLC on a C 18 column coupled to a radioactivity monitor led to the sensitive (⩽ 5 p M ) and specific determination of tyrosine sulfate-containing peptides.