PREPARATION OF BR-77 LABELED PROTEINS USING BROMOPEROXIDASE

The halogenating enzyme bromoperoxidase (BPO, EC 1.11.1.7), isolated f rom the brown algae Ascophyllum nodosum, was used to catalyze the radi obromination of an anti-hPLAP monoclonal antibody. Radiobromination of bovine serum albumin was also performed and used as control method. T he proteins are labeled with bromine-77, produced by the As-74 (alpha, 2n) Br-77 reaction. The essential reaction parameters, such as concen tration of protein and hydrogen peroxide, the amount of bromoperoxidas e, the pH of the reaction mixture, the reaction time and temperature w ere optimized. The immunoreactivity of the radiolabeled monoclonal ant ibody was checked with a ''Sandwich'' ELISA.