C. Dosoretz et al., ENTRAPMENT OF PARATHION HYDROLASE FROM PSEUDOMONAS SPP IN SOL-GEL GLASS, JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY, 7(1-2), 1996, pp. 7-11
The present work reports on the entrapment of parathion hydrolase from
Pseudomonas spp. into the sol-gel glass matrix. Enzyme entrapment was
studied in the range of 0.01-0.25 U, and compared with the activity o
f the free, non-immobilized enzyme. The reaction catalyzed by the entr
apped enzyme was almost two orders of magnitude slower than with the f
ree enzyme. Addition of surfactants slightly increased the parathion h
ydrolysis rate, and the addition of ethanol almost doubled it. However
, this increase of reaction rate cannot by itself explain the decrease
of activity, suggesting that irreversible damage to the enzyme during
gelation, rather than diffusion limitation throughout the,eel-glass s
tructure, is the main cause for the decrease of activity. Regardless o
f damage to the enzyme during gelation, the remaining entrapped active
fraction displayed stability even after eleven days, during successiv
e cycles of the same entrapped enzyme batch, each for 24 h. The sol-ge
l entrapped enzyme retained relatively good activity for several month
s when stored as a dry powder, and over a year when kept in buffer sol
ution, at ambient conditions. The results obtained may give a rise to
the use of entrapped parathion hydrolase for simple on-field bio-detec
tion of organophosphates.