An enhancement in the activity of papain (EC 3.4.22.2) was described in mixed reverse micellar systems containing Tween80 compared with those without Tween80. By the use of these media, the hydrolytic and synthesis activities of papain were investigated in detail, respectively for the hydrolysis of N-a-benzoyl-L-arginine-p-nitroaniline (BNPNA) and the synthesis of the dipeptide ZGly-L-PheOMe (ZGPM). The reaction medium conditions (W 0 , pH and Tween80 concentration) were optimized for both the hydrolytic and synthesis reactions. The results showed a pronounced increase in the papain activity when a moderate amount of Tween80 was added into sodium di-2-ethylhexylsulfosuccinate (AOT) or tetradecyltrimethylammonium bromide (TTAB) reverse micelles, either in the yield of dipeptide synthesis or in the initial rate of BNPNA hydrolysis. In addition, a mechanism to explain the enhancement of enzymatic activity was proposed according to the change of the optimal parameters in the mixed and non-mixed reverse micellar systems, which is associated with the environmental polarity surrounding the solubilised enzyme molecules.
An approach has been developed for predicting the change of the aqueous phase pH due to the partition of amino acid substrates in aqueous±organic biphasic systems. In the model reaction of papain-catalyzed synthesis of N-benzyloxycarbonyl-glycine-L-phenylalanine methyl ester (ZGPM) in an aqueous±ethyl acetate system, the effects of the initial aqueous phase pH and phase volume ratio on the ®nal aqueous phase pH, and the change of the ®nal aqueous phase pH during the course of ZGPM synthesis, are investigated. The results suggest that the approach is useful for selecting optimum reaction conditions for peptide synthesis not only in the aqueous±organic biphasic systems with free or immobilized enzymes but also with an immobilized enzyme in an organic solvent.
The spectra of the dielectric constant vs. the measuring temperature and of the dielectric constant vs. the measuring frequency for the nanostructured rutile bulk samples prepared under different pressures were investigated. It can be observed that when the measuring frequency ω2 times higher than that in the high frequency range. Furthermore, with the increment of the pressure, the dielectric constant rises and dielectric loss decreases and shifts towards the low frequency. For the samples formed under 1.0 GPa, two peaks appear in the spectrum of dielectric constant vs. the measuring temperature, and their peak positions are 50℃ and 300℃ , respectively. According to dielectric polarization theory, it can be supposed that high dielectric constant of nanostructured rutile arises mainly from the electronic relaxation polarization, which takes place inside the particle components of nanostructured rutile, and the rotation direction polarization, which is established in interfaces of nanostructured rutile, The 50℃ peak and the 300 ℃ peak are, respectively, attributed to the electronic relaxation polarization and the rotation direction polarization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.