Search
Filter Results
- Resource Type
- Article1
- Book1
- Book Digital1
- Journal1
- Article Type
- Research Support, U.S. Gov't, P.H.S.1
- Result From
- Lane Catalog1
- PubMed1
- SearchWorks (biomedical subset) 1
-
Year
- Journal Title
- Biochim Biophys Acta1
Search Results
Sort by
- JournalDigital Access Wiley v. 78-89, 1970-81.
- ArticleKnight LC, Welch MJ.Biochim Biophys Acta. 1978 Jun 21;534(2):185-95.The sites of radiohalogenation in proteins vary with the labeling method and the pH of the labeling reaciton. We have directly halogenated albumin with carrier-free radioiodide by three methods (pH range 2.2--9.3), and with carrier-free radiobromide by the chloroperoxidase method (pH range 2.2--4.6). Albumin was also indirectly halogenated by attaching a radioiodinated acylating agent, N-succinimidyl-3-(4-hydroxyphenyl) propionate (SHPP). The labeled proteins were proteolyzed enzymatically at neutral pH and the labeled amino acids produced were analyzed by liquid chromatography. Iodination at pH 7 yielded predominantly monoiodotyrosine, but at lower pH, fewer tyrosyl residues are labeled and a greater number of unstable sulfur-iodine bonds are formed at cysteinyl residues. Bromination with chloroperoxidase resulted in a high degree of labeling of cysteinyl residues at pH 2.8, the condition for optimum activity of this halogenating enzyme. Indirect halogenation with SHPP resulted in labeling of mid-chain lysyl, histidyl and tyrosyl residues.