Synthesis of Tritiated Glutamic Acid and Pyroglutamate

摘要

It was shown that introduction of tritium directly into glutamic acid does not afford a highly labeled product (at 160 degrees C, a specimen with a specific radioactivity of 3-5 Ci/mmol was formed; at 180 degrees C, the specific radioactivity was 26 Ci/mmol; and at 200 degrees C, the compound strongly degraded). Heating a mixture of 5% Pd/Al2O3 with alumina-supported sodium glutamate at 220 degrees C for 7.5 min gave mainly [H-3]pyroglutamate. After isolation and purification of [H-3]pyroglutamate, its solution in 1 N HCl was heated at 105 degrees C for 20 h. This yielded [H-3]glutamic acid with a specific radioactivity of 40 Ci/mmol.