RESUMO
Nanocapsuling organophosphorus hydrolase (OPH) is a promising strategy, which can improve OPH stability and put it into practical application. Nanocapsule can protect OPH from deactivation, but on the other hand it may block the contact of enzymes and substrates to some extent. Thus, it is worth exploring the influences of nanocapsule density on the enzyme activity and stability. In this study, OPH surface was modified by N-acryloxysuccinimide (NAS), and then the in situ radical polymerization technique was applied to construct a polymer shell around the surface to form the OPH nanocapsule (nOPH). Transmission electron microscope (TEM) and Fourier Transform Infrared (FTIR) was used to characterize the structure of nOPH. The nOPH activity is not influenced by the presence of nanocapsule when the feed ratio of NAS to OPH is below 75. On the contrary, it decreases with the increasing of NAS feed ratio when it is above 75. Furthermore, nOPH activities at high temperatures and in 20% DMSO solutions both first increase and then decrease with the increasing of NAS feed ratio. The results showed that the appropriate density of the nanocapsule could retain the enzyme activity to the maximum extent during the preparation of nOPH nanocapsule, and significantly improve its thermal stability and organic solvent stability. Hence, the results are of great significance to further realize the OPH practical application.