Pilot-scale production of human serum butyrylcholinesterase suitable for use as a bioscavenger against nerve agent toxicity

Human serum butyrylcholinesterase (Hu BChE) is currently the most appropriate candidate for the prophylaxis of humans against organophosphate (OP) nerve agent toxicity. It is estimated that a dose of 200 mg will protect a human against 2× LD50 of soman, which means that gram quantities of enzyme are needed for human clinical studies. Toward this effort, we report the development of the first procedure that is suitable for the pilot-scale purification of Hu BChE from Cohn fraction IV-4 paste. This procedure involved resuspension of Cohn fraction IV-4 paste, followed by procainamide affinity and DEAE anion-exchange chromatography. The procedure yielded 6–7 g (4.3–5 million U) of purified enzyme from 80 kg of Cohn fraction IV-4 paste. The enzyme was >97% pure as judged by a specific activity of ∼700 U/mg and a major band with a subunit molecular weight of 85 kDa on SDS-PAGE. The high yield and purity obtained suggest that this manufacturing procedure is suitable for the pre-clinical production of Hu BChE.