Differences in the sites of iodination of proteins following four methods of radioiodination

Kenneth A. Krohn, Linda C. Knight, John F. Harwig, Michael J. Welch

Research output: Contribution to journalArticle

58 Scopus citations

Abstract

The rate of deiodination of radioiodinated proteins varies with the method of iodination. To elucidate differences in the iodinated protein labeled by various methods, we have hydrolyzed fibrinogen and several small peptides iodinated by the iodine monochloride, chloramine-T, electrolytic and enzymatic methods. Under conditions of either acidic or basic proteolysis, extensive deiodination occurred and the major product was I-. When a protease of Streptomyces griseus was used, radioiodinated fibrinogen and other polypeptides were degraded to single iodinated amino acid residues and only a small yield of I-. The iodinated amino acids resulting from proteolysis were separated by ion-exchange chromatography. The iodine monochloride and enzymatic methods yielded largely iodotyrosine with small amounts of other iodinated amino acids. The chloramine-T product spectrum varied with the chloramine-T:protein ratio, whereas the electrolytic method yield was a complex function of the reaction conditions. The different methods of iodination lead to some differences in the site of iodination which correlate with stability of the protein-iodine bond.

Original languageEnglish (US)
Pages (from-to)497-505
Number of pages9
JournalBBA - Protein Structure
Volume490
Issue number2
DOIs
StatePublished - Feb 22 1977

ASJC Scopus subject areas

  • Medicine(all)

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