title: Synthesis and properties of sulfhydryl-group-specific reagents containing 125I.
abstract: 125I-containing compounds that react specifically with sulfhydryl groups were prepared in yields of 30 to 40% on the basis of starting 125I quantity. The synthetic precursors were commercially available heterobifunctional crosslinkers and the peptide L-arginyl-L-tyrosine. Two types of sulfhydryl specific reagents were prepared: 3-(2-pyridyldithio)propionylarginyl-[125I]-monoiodotyrosine, which permits reversible incorporation of 125I at sulfhydryl sites, and 3-maleimidopropionylarginyl- [125I]monoiodotyrosine, an irreversible labeling reagent. These products were isolated in a highly radiochemically pure form by C18 HPLC. The second-order rate constants for the reaction of 3-(2-pyridyldithio)propionylarginylmonoiodotyrosine and 3-maleimidopropionylarginylmonoiodotyrosine with N-acetylcysteine were 28 +/- 3 M-1 s-1 and 154 +/- 4 M-1 s-1, respectively, at pH 7.3. Storage of carrier-free 3-(2-pyridyldithio)propionylarginyl-[125I]monoiodotyrosine and 3-maleimidopropionylarginyl-[125I]monoiodotyrosine at -80 degrees C at a radioactive concentration of 0.4 mCi/ml resulted in conversion of 125I to species that did not react covalently with sulfhydryl groups. This process occurred with first-order kinetics and a t1/2 of 5.7 days for the pyridyldithio compound and 7.5 days for the maleimido compound. No conversion was observed during storage at -80 degrees C at radioactive concentrations of 0.02 mCi/ml or less. The labeling properties of these compounds were examined using red blood cell proteins as a test system. 3-(2-Pyridyldithio)propionylarginyl- [125I]monoiodotyrosine and maleimidopropionylarginyl-[125I]monoiodotyrosine reacted preferentially with membrane - associated sulfhydryl groups when incubated with intact red blood cells.
authors.affiliation: Department of Biochemistry, University of Nebraska, Lincoln 68583-0718.
authors.forename: R J
authors.initials: RJ
authors.lastname: Krueger
authors.forename: C
authors.initials: C
authors.lastname: Lin
authors.forename: J A
authors.initials: JA
authors.lastname: Frank
mesh_terms: D001798:Blood Proteins / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004151:Dipeptides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000737:chemistry; D006801:Humans; D007457:Iodine Radioisotopes; D007470:Monoiodotyrosine / Q000031:analogs & derivatives*; D013438:Sulfhydryl Compounds / Q000032:analysis* / Q000737:chemistry
chemical_list: D001798:Blood Proteins; D003432:Cross-Linking Reagents; D004151:Dipeptides; D007457:Iodine Radioisotopes; D013438:Sulfhydryl Compounds; C073052:3-(2-pyridyldithio)propionylarginylmonoiodotyrosine; C073051:3-maleimidopropionylarginylmonoiodotyrosine; D007470:Monoiodotyrosine