Polyethylene glycosylation prolongs the stability of recombinant human paraoxonase-1.

Paraoxonase-1 (PON1) is a native enzyme that is synthesized in the liver and is capable of hydrolyzing organophosphates (OPs). It is regarded as part of a promising approach for the pretreatment and therapy of OP poisoning. Previous experiments with purified rabbit serum PON1 have established that it can protect rats against many OP exposures. In the current paper, we described a preparation of active recombinant human PON1 (rHuPON1) by engineering an Escherichia coli expression system. Recombinant HuPON1 was purified by Ni-NTA affinity chromatography followed by DEAE sepharose fast-flow chromatography. After purification, rHuPON1 was chemically modified with polyethyleneglycol (PEG)-20K. Recombinant HuPON1 exhibited a mean residence time (MRT) of 8.9h, which was threefold shorter than that of native HuPON1 in rats. However, rHuPON1 chemically modified with PEG-20K displayed an MRT of 19.5h, suggesting that PEG modification can prolong the circulatory stability of rHuPON1. PEG-rHuPON1 had a catalytic efficiency sufficient in protecting rats against OP poisoning, as measured by acetylcholinesterase activity in tissues and signs after poisoning. Crown