The preparation and characterization of phosphorylated derivatives of histidine

1. Phosphorylated derivatives of histidine were synthesized and studied in order to provide a better understanding of the chemistry of phosphohistidine-containing proteins. 1-Phosphohistidine, 1,3-diphosphohistidine, α, 1,3-triphosphohistidine, and phosphorylated derivatives of α-N-acetylhistidine were prepared by reactions with POCl3 or phosphoramidate. The compounds were purified by ion-exchange chromatography and characterized by the phosphate: histidine ratio, electrophoretic behavior, and ultraviolet spectra. 2. The rates of hydrolysis of these compounds, as well as 3-phosphohistidine, phosphoimidazole, and 1,3-diphosphoimidazole, were determined over a wide range of H+ concentrations. In strongly acidic solution all of the compounds appeared to be hydrolyzed by the same mechanism. In all cases the N-phosphoryl bond was hydrolyzed more readily if a proton or phosphoryl group were substituted on the other ring nitrogen, and histidine derivatives were less stable than the corresponding imidazole derivatives. 3. For both mono- and diphosphoryl derivatives of histidine, the N-1 phosphoryl group was hydrolyzed and transferred to other imidazole compounds more readily than the N-3 phosphoryl group. The greater reactivity at the N-1 position is partially due to the presence of the protonated α-amino group. 4. In aqueous solution, 1-phosphohistidine is rapidly converted to 3-phosphohistidine, histidine and inorganic phosphate.