The radioactive labeling of proteins with an iodinated amidination reagent

✍ Scribed by Frederick T. Wood; Michael M. Wu; John C. Gerhart

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 658 KB
• Volume: 69
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(75)90136-0

✦ Synopsis

An iodinated derivative of the imidoester methyl p-hydroxybenzimidate HCI (MPHBIM) has been synthesized for the selective labeling of proteins to high specific activity with radioactive iodine. In the first step, MPHBIM is reacted with radioactive iodide in the presence of chloramine T, and the iodinated derivative is precipitated from acidified solution to achieve partial purification. In the second step, the iodinated imidoester is redissolved at slightly alkaline pH and reacted with protein amino groups, to which it couples by amidine linkage. The coupling reaction proceeds in the presence of sulfhydryl reagents used to protect proteins. The main advantage of this two-step labeling procedure is that it avoids direct contact of the protein with potentially deleterious materials such as chloramine T or contaminants of the radioactive iodide.