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Tuning dimeric formate dehydrogenases reduction/oxidation activities by immobilization

Yildirim, Deniz, Alagöz, Dilek, Toprak, Ali, Tükel, Seyhan, Fernandez-Lafuente, Roberto
Process biochemistry 2019 v.85 pp. 97-105
Candida boidinii, adsorption, biocatalysts, calcium alginate, carbon dioxide, carbonates, encapsulation, formate dehydrogenase, formates, formic acid, half life, hydrogen, immobilized enzymes, montmorillonite, oxidation, pH, polyvinyl alcohol, sodium bicarbonate, thermal stability
Three differently immobilized preparations of an enzyme extract from Candida boidinii containing a NAD+-dependent formate dehydrogenase (CbFDH) were prepared by encapsulation using calcium alginate (CbFDH-Alg) or polyvinyl alcohol (CbFDH-PVA) or by adsorption on montmorillonite K 10 (CbFDH-Mont). All FDH preparations were characterized in terms of both oxidation and reduction activities. For the formic oxidation activity, all immobilized FDHs had 100% activity at pH 8.0 and 50 °C, as the soluble enzyme. Among the immobilized biocatalyst, only CbFDH-PVA showed activity in the reduction of hydrogen carbonate and had 100% activity at pH 6.0 and 40 °C, as the soluble enzyme. The half-life values of immobilized enzymes increased by at least 3.1-folds compared to the soluble enzyme. Formic acid was produced from HCO3− as a source of carbon dioxide using soluble CbFDH and CbFDH-PVA and the formic acid yields were determined as 80 and 92%, respectively for soluble CbFDH and CbFDH-PVA after 240 min reaction. CbFDH-Alg, CbFDH-PVA and CbFDH-Mont retained 40.1, 49.8 and 26.1% of their initial activities after 10 reuses in formate oxidation reaction. The remaining reduction activity of CbFDH-PVA was 30% after 10 reuses. These results show the CbFDH immobilization following different protocols strongly alter their oxidation/reduction activities.