N-iodoacetyltyramine: Preparation and use in 125I labeling by alkylation of sulfhydryl groups

✍ Scribed by Chaomei Lin; Kevin A. Mihal; Rick J. Krueger

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 928 KB
• Volume: 179
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(89)90150-4

✦ Synopsis

Preparation and use of N-iodoacetyltyramine in generation of 125I-labeled compounds is described. The kinetics of alkylation of N-acetylcysteine by N-iodoacetyltyramine (k2 = 3.0 M-1 s-1) and N-chloroacetyltyramine (k2 = 0.12 M-1 s-1) indicate that N-iodoacetyltyramine is more useful for labeling sulfhydryl-containing compounds to high specific activity with 125I. Conditions for preparation of carrier-free 125I-labeled N-iodoacetyl-3-monoiodotyramine in 50% yield based on starting iodide are described. The high degree of group specificity of N-iodoacetyl-3-monoiodotyramine reaction with sulfhydryl groups is demonstrated by the high reactivity toward sulfhydryl-containing bovine serum albumin and low reactivity toward N-ethylmaleimide-blocked bovine serum albumin and IgG. 125I-labeled N-iodoacetyl-3-monoiodotyramine was also used to prepare an 125I-labeled ACTH derivative that retains full biological activity, further demonstrating the selectivity toward reactions with sulfhydryl groups.