Reaction of β-propiolactone with amino acids and its specificity for methionine

Abstract

1. The reactions of β-propiolactone with amino acids were investigated under various conditions of pH and temperature to find those under which the reagent acted with specificity. 2. At pH9·0 and 22°, after 15min. of reaction, at least 85% of each amino acid had reacted, methionine and cystine being the most reactive. 3. At pH7·0 and 22° most amino acids reacted; methionine, cystine and histidine reacted almost entirely, and proline and lysine to a significantly smaller extent. 4. At pH3·0 and 22° further specificity was obtained; methionine and cystine were the only reactive amino acids. 5. Reaction at pH3·0 and 0° was specific for methionine; it was the only amino acid modified even after 145hr. of reaction.