Comparison of125I-Labeled and14C-Labeled Peptides of the Major outer Membrane Protein ofChlamydia TrachomatisStrain L2/434 separated by High-Performance Liquid Chromatography

Abstract

If in-gel chloramine-T radioiodination adequately labels OM [outer membrane] proteins to allow for accurate and precise structural comparison of these molecules was determined. Therefore, intrinsically 14C-amino acid labeled proteins and 125I-labeled proteins were cleaved with 2 endopeptidic reagents and the peptide fragments separated by HPLC [high-performance liquid chromatography]. A comparison of retention times of the fragments, as determined by differential radiation counting, thus indicated whether 125I-labeling identified of all the peptide peaks seen in the 14C-labeled proteins. Apparently, radioiodination yields complete and accurate information about the primary structure of OM proteins. In addition, it permits the use of extremely small amounts of protein allowing for method optimization and multiple separations to insure reproducibility.