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Abstract
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Catalase (H2O2. H2O2Oxidoreductase EC 1.11.1.6) is an antioxidant enzyme that catalyzes hydrogen peroxide to water and oxygen molecules. It is regarding to catalase performance and progressing in nanotechnology, in the present study, catalase nanoparticles were prepared by desolvation method using ethanol and glutaraldehyde as desolvating and crosslinker agent respectively. The factors such as amount of ethanol andglutaraldehyde, stirring rate, synthesis time were optimized. Properties of nanoparticles including particle size, morphology and structural changes were characterizedusing spectroscopic techniques such as UV-Visible, FTIR, DLS and SEM. Also their kinetic parameters were determined on based Michaelis-Menten equation. The study of the effects of DTAB and SDS as typical cationic and anionic surfactantsrespectively on catalase nanoparticles were investigated forits thermodynamical stability. The results of the optimization studies revealed that for the mixture of 1.0 mg enzyme, 4 ml ethanol, 0.12 mg/ml of glutaraldehyde and phosphate buffer 50 mM (pH 7.0), up to 70% of the enzyme activity remained. In these conditions the average radius of the particles was 53.78 nm. Investigation of the UV-Vis and FTIR spectra showed that the formation of the nanoparticles caused the structural changes of the protein at tertiary and secondary level. The study of the effects of DTAB and SDS as cationic and anionic surfactants respectively, on the native and enzyme nanoparticles approve that the nanoparticles show a lower tendency to interact with the surfactants. In other words, the conformational changes in the protein nanoparticles reduce the protein denaturation. Comparing the kinetics parameters of the native enzyme and enzyme nanoparticles showed both Km and Vmax were reduced for the synthesized nanoparticles
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