No abstract

NAD-dependent formate dehydrogenases (FDH, EC 1.2.1.2), providing energy to the cell in methylotrophic microorganisms, are stress proteins in higher plants and the level of FDH expression increases under several abiotic and biotic stress conditions. They are biotechnologically important enzymes in NAD(P)H regeneration as well as CO reduction. Here, the truncated form of the cDNA was cloned into pQE-2 vector, and overexpressed in DH5α-T1 cells. Recombinant GhFDH1 was purified 26.3-fold with a yield of 87.3%. Optimum activity was observed at pH 7.0, when substrate is formate. Kinetic analyses suggest that GhFDH1 has considerably high affinity to formate (0.76 ± 0.07 mM) and NAD (0.06 ± 0.01 mM). At the same time, the affinity (1.98 ± 0.4 mM) and catalytic efficiency (0.0041) values of the enzyme for NADP show that GhFDH1 is a valuable enzyme for protein engineering studies that is trying to change the coenzyme preference from NAD to NADP which has a much higher cost than that of NAD. Improving the NADP specificity is important for NADPH regeneration which is an important coenzyme used in many biotechnological production processes. The value of GhFDH1 is 53.3 °C and the highest enzyme activity is measured at 30 °C with a half-life of 61 h. Whilst further improvements are still required, the obtained results show that GhFDH1 is a promising enzyme for NAD(P)H regeneration for its prominent thermostability and NADP specificity.

A copper oxide (CuO) nanoparticle, a transition metal oxide with a wide variety of easy production methods, can be used as an antimicrobial agent against various types of bacteria. CuO nanoparticles were produced by the sol–gel method, annealed and structural characteristics and antimicrobial properties of these particles were investigated. Single-phase monoclinic of CuO nanoparticle formation was confirmed by X-ray powder diffraction (XRD) spectra, FTIR techniques, differential scanning calorimetry with thermal gravimetry were used to characterize. It was determined that annealing in the temperature range of 150–900∘C affects both structure and particle size and antimicrobial characteristics. CuO nanoparticle size was found to be between about 25–70[Formula: see text]nm at 150–900∘C annealing temperature, which does not have this wide temperature range in the literature. These results were supported by the TEM micrographs of the CuO nanoparticles observed at 150∘C and 900∘C. The antimicrobial activity of the synthesized nanoparticles was tested with the disc diffusion assay against Staphylococcus aureus, Escherichia coli, Agrobacterium tumefaciens, and yeast Pichia pastoris. The antimicrobial properties of the nanoparticles first increased and then decreased and disappeared as the annealing temperature increased. The antimicrobial properties of CuO nanoparticles disappeared at 750∘C and above, while the maximum antimicrobial effect was at 300∘C. The inhibition zones were examined and similar results were observed in all tested microorganisms.