Investigations of high specific activity solid-phase peptide synthesis

There is increasing interest in biological and pharmaceutical research in biotechnology, and drugs based on endogenous peptides. As a result, the demand for high specific activity radiolabeled peptides will continue to increase. It therefore becomes important that there be a variety of effective methods available for the preparation of these compounds, labeled in specific sites. Investigations to date have shown that in the coupling of labeled amino acids in solid-phase peptide synthesis, the efficiency of incorporation into the solid phase increases with decreasing proportions of labeled amino acid, but the fraction of bound radioactivity recoverable as labeled peptide decreases correspondingly. Increasing the reaction time in the coupling compensates to some extent for the low amino acid to resin ratios and the more dilute reaction conditions.