HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF SULFATED PEPTIDES IN HUMAN HEMOFILTRATE USING A RADIOACTIVITY MONITOR

Specific labeling of tyrosine sulfate-containing peptides was achieved using a differential iodination approach. In a complex peptide mixtur e from human hemofiltrate, cold iodination to saturate free iodine bin ding 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 d erivatization and by spiking with a sulfated cholecystokinin fragment (CCK4-S). Separation of the peptide mixture with RP-HPLC on a C-18 col umn coupled to a radioactivity monitor led to the sensitive (less than or equal to 5 pM) and specific determination of tyrosine sulfateconta ining peptides.