Authors: OkJae Sohn ChunKwang Kim Jong Il Rhee
Publish Date: 2009/02/03
Volume: 13, Issue: 6, Pages: 716-723
Abstract
Glucose oxidase GOD and lactate dehydrogenase LDH were immobilized onto magnetic nanoparticles viz Fe3O4 via carbodiimide and glutaraldehyde The immobilization efficiency was largely dependent upon the immobilization time and concentration of glutaraldehyde The magnetic nanoparticles had a mean diameter of 93 nm and were superparamagnetic The immobilization of GOD and LDH on the nanoparticles slightly decreased their saturation magnetization However the FTIR spectra showed that GOD and LDH were immobilized onto the nanoparticles by different binding mechanisms the reason for which was not well explained The optimum pH values of the immobilized GOD and LDH were changed to 8 and 10 respectively The free and immobilized enzyme kinetic parameters Km and Vmax were determined by MichaelisMenten enzyme kinetics The Km values for free and immobilized GOD were 0168 and 0324 mM respectively while those for free and immobilized LDH were 019 and 0163 mM for NAD and 2976 and 4785 mM for lactate respectively High operational stability was observed with more than 80 of the initial enzyme activity being retained for the immobilized GOD up to 12 h and for the immobilized LDH up to 24 h The immobilized GOD was applied to a sequential injection analysis system for the application of bioprocess monitoring
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