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 Aim and Background . Metalloproteases have numerous industrial applications such as peptide and aspartame synthesis. However, their application is limited by instability as a result of autolysis. . In the present study, following purification, biochemical properties of a metalloprotease (elastase) from Pseudomonas aeruginosa have been investigated.

Materials and Methods. Recombinant protein has been purified from E. coli by affinity chromatography. Temperature dependence of enzyme activity and optimum temperature has been measured using a plot of enzyme activity versus different temperatures. Optimum temperature of enzyme activity has been determined within a mix buffer solvent by activity measurements at different pHs, and the inactivation rate, t_1/2 and thermodynamic parameters of inactivation have been determined using irreversible thermoinactivation.

Results. Optimum temperature was 60°C in the presence of 0, 5 and 10 mM CaCl₂, and optimum pH was 8.5. Inactivation rate was increased with elevation of temperature from 55 to 80°C. Half-life of thermoinactivation ( t_1/2 ) was 150, 112, 47, 32, 18, 8 and 4 min at 55, 60, 65, 70, 75 and 80°C, respectively. E_a, D H ^# , D S ^# and D G ^# was 37.70, 37.02, 23.61 kcal/mol, respectively, and k_inactivation was 4.49 ´ 10³ s^-1.

Conclusion . Pseudomonas aeruginosa elastase can be considered between thermophilic and mesophilic enzymes. Optimum temperature did not alter in different calcium concentrations which imply that elastase stability is Ca-independent.

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Aim and Background:
Liposomal vesicles provide the possibility of loading lipophilic drugs into phospholipids bilayers and water-soluble (hydrophilic) aqueous phase. The present study was aimed on the evaluation of the properties of liposomal doxorubicin loaded into liposome by both active and passive procedures in terms of drug loading and release.
Material and methods:
Dipalmitoyl glycerol phospholipid glycerol, cholesterol and DSPE-mPEG 2000 was used for synthesis of nanoliposome. Then, doxorubicin loading was performed by passive (thin film hydration) and active (according to pH gradient) methods. The average diameter of nanoparticls was measured with Zeta Sizer. And the amount of drug loading and release was performed using dialysis.
Results:
The average size of nanoparticles were 138.6 ± 4.9 nm  and 105.9 ± 3.8 nm for thin film hydration method, and pH gradient method, respectively. And drug loading efficacy of doxorubicin-containing nanoliposomes was 89±4.35 for pH gradient method and 15.65±8.65 for thin film method. The accumulated amount of drug release during 48 hours in PBS at pH=7.4, was determined 78% and 24% for hydration thin film method pH gradient method, respectively.
Conclusion:
This study shows that nanoliposomal doxorubicin prepared by active method, was more effective than that the passive method. Our prepared nanoformulation was also sensitive to pH of medium.