Levin, Artem and Hartl, Andreas and Reiser, Oliver and Czeslik, Claus (2019) High-pressure study of magnetic nanoparticles with a polyelectrolyte brush as carrier particles for enzymes. COLLOIDS AND SURFACES B-BIOINTERFACES, 182: 110344. ISSN 0927-7765, 1873-4367
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The recovery of enzymes from a reaction medium can be achieved in a convenient way by using magnetic nanoparticles (MNP) as carriers. Here, we present MNP with a polyelectrolyte brush composed of poly(ethylene imine) (PEI) to provide a benign environment for the immobilized enzyme molecules. Yeast alcohol dehydrogenase (ADH) has been tested for enzymatic activity when it is free in solution or adsorbed on the PEI brush-MNP. Furthermore, the effect of pressure on the enzymatic activity has been studied to reveal activation volumes, which are a sensitive probe of the transition state geometry. The results of this study indicate that the secondary structure of ADH is pressure -stable up to 9 kbar. The enzymatic activity of ADH can be analyzed using Michaelis-Menten kinetics free in solution and adsorbed on the PEI brush-MNP. Remarkably, no significant changes of the Michaelis constant and the activation volume are observed upon adsorption. Thus, it can be assumed that the turnover number of ADH is also the same in the free and adsorbed state. However, the maximum enzymatic rate is reduced when ADH is adsorbed, which must be explained by a lower effective enzyme concentration due to steric hindrance of the enzyme inside the PEI brush of the MNP. In this way, the pressure experiments carried out in this study enable a distinction between steric and kinetic effects on the enzymatic rate of adsorbed ADH.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | YEAST ALCOHOL-DEHYDROGENASE; ENZYMATIC CATALYSIS; SECONDARY STRUCTURE; PROTEIN ADSORPTION; POLYMER; CONFORMATION; TEMPERATURE; STABILITY; REUSE; Magnetic nanoparticle; Polyelectrolyte brush; Alcohol dehydrogenase; Protein adsorption; Pressure; Activation volume |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Oliver Reiser |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 24 Mar 2020 12:17 |
| Last Modified: | 24 Mar 2020 12:17 |
| URI: | https://pred.uni-regensburg.de/id/eprint/26128 |
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