chloramine-t and cholecystokinin-(26-33)

A sequential approach was developed to label tyrosine sulfate and peptides containing tyrosine sulfate selectively. Amino acids and peptides containing tyrosine and tyrosine sulfate were first iodinated using chloramine-T-method. Reaction products were determined by RP-HPLC. Mono- and biiodination of tyrosine and several model peptides was achieved within 120 s incubation time. Iodination of free tyrosine sulfate and sulfated cholecystokinin26-33 was less than 5%. After desulfation of the reaction products with 1 N HCl successful radioiodination of desulfated tyrosine was carried out whereas tyrosine did incorporate radioactive iodine only 10%. As shown by RP-HPLC specific labeling of tyrosine sulfate containing peptides with 125iodine was achieved.

Topics: Amino Acid Sequence; Chloramines; Chromatography, High Pressure Liquid; Indicators and Reagents; Iodine; Iodine Radioisotopes; Kinetics; Molecular Sequence Data; Peptides; Sincalide; Sulfates; Sulfur Radioisotopes; Tosyl Compounds; Tyrosine