Specific types of white blood cells (eosinophils) can generate HOBr to inactivate invading pathogens. HOBr exists in equilibrium with additional brominating agents (e.g., BrCl, Br2, BrOCl, and Br2O), all of which can covalently modify biologically-important molecules, including amino acids. Previous findings have associated residues of halogenated biomolecules with inflammatory diseases such as asthma, arthritis, and Alzheimer's. The purpose of this research is to quantify regiospecific bromination rates of boc-L-phenylalanine (boc-Phe) as a model compound. Experiments were designed to permit quantification of the contributions of individual brominating agents toward overall bromination rates of boc-Phe. Time course reactions for boc-Phe were implemented under controlled conditions to test the effects of pH, chloride concentration, and bromide concentration on rates of brominated product formation. Reactors were analyzed using high-performance liquid chromatography with UV-vis detection. Results indicate boc-Phe can form two regiospecific brominated products.   Bromination rates increased with increasing concentrations of chloride and with decreasing pH. Compared to the significantly more nucleophilic amino acid tyrosine, the reactivity of boc-Phe toward brominating agents is much less, but nevertheless quantifiable. Unlike the monobrominated products of tyrosine, the brominated products of boc-Phe appear to be more stable toward subsequent bromination than is the parent compound. The potential biochemical implications of phenylalanine bromination will be discussed.

Reactivity of phenylalanine with brominating agents: Quantifying regiospecific rates of brominated phenylalanine formation

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.