ADH immobilized on derived attapulgite nanofibers via glutaraldehyde covalent binding retains higher activity over wider ranges of pH and temperature than those of the free enzyme. After shaking at 125 rpm at 35°C for 32 h, a rapid loss in activity is observed, and almost complete activity of immobilized enzyme is lost in 52 h. The activity of immobilized ADH decreases to 80% of its initial value after four cycles of operation and afterwards gradually decreases with every reuse, but it retains 42% activity after eight cycles for bioreduction of ethyl 3-oxobutyrate.
effects of salts on the rate constants of inactivation by heat of alcohol dehydrogenase YADH at 60.0°C. At high concentrations, some salts have stabilizing effects, while others are destabilizing. The effects of salts in the high concentration range examined can be described as follows: (decreased thermal stability) NaClO4, NaI = (C2H5)4NBr, NH4Br, NaBr = KBr = CsBr = (no addition), (CH3)4NBr, KCl, KF, Na2SO4 (increased thermal stability). The decreasing effect of NaClO4 controlls the thermal stability of the enzyme absolutely and is not compensated by the addition of Na2SO4, which stabilizes the enzyme
enzyme covalently immobilized to magnetic Fe3O4 nanoparticles via glutaraldehyde shows enhanced thermal stability and good durability in the repeated use after recovered by magnetic separations. Within 7 cycles of usage, the remaining activity is about 100%, 89.15%, 79.42%, 69.50%, 62.80%, 56.48%, and 48.26% of the first use
the presence of a second phase of a water-insoluble solvent like hexane or octane has only minor effects on the enzyme, which retains 80% of its activity, allowing the use of these solvents in aqueous/organic mixtures to increase the availability of low-water soluble substrates