• Applied Biological Chemistry
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• v.37 no.5
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• pp.397-401
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• 1994

Bioreduction with active dried baker's yeast proceeded smoothly in n-hexane, pentane or petroleum ether as an organic solvent system. Ethyl(1) and octyl 3-oxohexanoate(2) were reduced to $({\underline{R}})-ethyl(3)$ and $({\underline{S}})-octyl$ 3-hyroxy-hexanoate(4) with high enantiomeric excess, respectively.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.81-87
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• 2018

This research was done to investigate the bioreduction characteristics of perchlorate in raw sewage because sewage contains biodegradable organics and various microorganisms for biological perchlorate reduction. Two different types of sewage were tested for biological perchlorate reduction in the flasks. Sewage A was collected from the screening equipment and sewage B was collected from the primary settlement in the municipal wastewater treatment facilities. Perchlorate was completely reduced within 72hours from 8.2 and 10.4 mg/L in the sewage A and sewage B flask tests. When perchlorate and nitrate were added in sewage A, both perchlorate and nitrate were reduced. However, perchlorate and nitrate removal rates were 9.3% and 64.0% at 72hours in sewage B. Perchlorate reduction was significantly inhibited by high salinity(0.5% NaCl) in the sewage A and B. These results showed the sewage has potential for the biological perchlorate reduction in the sewage pipe.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.58-65
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• 2011

The bacterial uranium(VI) reduction and its resultant low solubility make this process an attractive option for removing U from groundwater. An impact of aqueous suspending iron phase, which is redox sensitive and ubiquitous in subsurface groundwater, on the U(VI) bioreduction by Shewanella putrefaciens CN32 was investigated. In our batch experiment, the U(VI) concentration ($5{\times}10^5M$) gradually decreased to a non-detectable level during the microbial respiration. However, when Fe(III) phase was suspended in solution, bioreduction of U(VI) was significantly suppressed due to a preferred reduction of Fe(III) instead of U(VI). This shows that the suspending amorphous Fe(III) phase can be a strong inhibitor to the U(VI) bioreduction. On the contrary, when iron was present as a soluble Fe(II) in the solution, the U(VI) removal was largely enhanced. The microbially-catalyzed U(VI) reduction resulted in an accumulation of solid-type U particles in and around the cells. Electron elemental investigations for the precipitates show that some background cations such as Ca and P were favorably coprecipitated with U. This implies that aqueous U tends to be stabilized by complexing with Ca or P ions, which easily diffuse and coprecipitate with U in and around the microbial cell.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.343-350
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• 2013

(R)-[3,5-Bis(trifluoromethyl)phenyl] ethanol is a key chiral intermediate for the synthesis of aprepitant. In this paper, an efficient synthetic process for (R)-[3,5- bis(trifluoromethyl)phenyl] ethanol was developed via the asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone, catalyzed by Leifsonia xyli CCTCC M 2010241 cells using isopropanol as the co-substrate for cofactor recycling. Firstly, the substrate and product solubility and cell membrane permeability of biocatalysts were evaluated with different co-substrate additions into the reaction system, in which isopropanol manifested as the best hydrogen donor of coupled NADH regeneration during the bioreduction of 3,5-bis(trifluoromethyl) acetophenone. Subsequently, the optimization of parameters for the bioreduction were undertaken to improve the effectiveness of the process. The determined efficient reaction system contained 200mM of 3,5-bis(trifluoromethyl) acetophenone, 20% (v/v) of isopropanol, and 300 g/l of wet cells. The bioreduction was executed at $30^{\circ}C$ and 200 rpm for 30 h, and 91.8% of product yield with 99.9% of enantiometric excess (e.e.) was obtained. The established bioreduction reaction system could tolerate higher substrate concentrations of 3,5- bis(trifluoromethyl) acetophenone, and afforded a satisfactory yield and excellent product e.e. for the desired (R)-chiral alcohol, thus providing an alternative to the chemical synthesis of (R)-[3,5-bis(trifluoromethyl)phenyl] ethanol.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1769-1776
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• 2019

Ethyl (S)-3-hydroxy-3-(2-thienyl) propanoate ((S)-HEES) acts as a key chiral intermediate for the blockbuster antidepressant drug duloxetine, which can be achieved via the stereoselective bioreduction of ethyl 3-oxo-3-(2-thienyl) propanoate (KEES) that contains a 3-oxoacyl structure. The sequences of the short-chain dehydrogenase/reductases from Chryseobacterium sp. CA49 were analyzed, and the putative 3-oxoacyl-acyl-carrier-protein reductase, ChKRED12, was able to stereoselectively catalyze the NADPH-dependent reduction to produce (S)-HEES. The reductase activity of ChKRED12 towards other substrates with 3-oxoacyl structure were confirmed with excellent stereoselectivity (>99% enantiomeric excess) in most cases. When coupled with a cofactor recycling system using glucose dehydrogenase, the ChKRED12 was able to catalyze the complete conversion of 100 g/l KEES within 12 h, yielding the enantiopure product with >99% ee, showing a remarkable potential to produce (S)-HEES.

• BMB Reports
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• v.34 no.3
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• pp.225-229
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• 2001

Besides a variety of quinones, purified bovine liver quinone reductase catalyzed the reduction of N,N-p-nitrosoaniline to N,N-dimethyl-p-phenylenediamine. The formation of N,N-dimethyl-p-phenylenediamine was identified by TLC, GC, GC-MS and NMR. Quinone reductase can utilize either NADH or NADPH as a source of reducing equivalents. The apparent Km for 1,4-benzoquinone and N,N-dimethyl-p-nitrosoaniline was 1.64 mM and 0.22 mM, respectively The reduction of N,N-dimethyl-p-nitrosoaniline was almost entirely hampered by dicumarol or Cibacron blue 3GA, potent inhibitors of mammalian quinone reductase. During the bovine liver quinone reductase-catalyzed reduction of N,N-dimethyl-p-nitrosoaniline, benzoquinonediiminium ion was produced.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.48-53
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• 2006

The asymmetric biosynthesis of ethyl (S)-4-chloro-3-hydrobutanoate from ethyl 4-chloro-3-oxobutanoate was investigated by using whole cells of Candida magnoliae JX120-3 without the addition of glucose dehydrogenase or $NADP^+/NADPH$. In a one-phase system, the bioconversion yield was seriously affected on the addition of 12.1 g/L ethyl 4-chloro-3-oxobutanoate. In order to reduce this substrate inhibition, a water/ n-butyl acetate two-phase system was developed, and the bioreduction conditions optimized with regard to the yield and product enantiometric excess value. The optimal conditions were as following: water to n-butyl acetate volume ratio of 1:1, 4.0 g DCW/L active cells, 50 g/L glucose and $35^{\circ}C$. By adopting a dropwise substrate feeding strategy, high concentration of ethyl 4-chloro-3-oxobutanoate (60 g/L) could be asymmetrically reduced to ethyl (S)-4-chloro-3-hydrobutanoate with high yield (93.8%) and high enantiometric excess value (92.7%).

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.690-698
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• 2012

Cr-B2, a Gram-negative hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr-B2 exhibited a resistance for 1,100 mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as $Ni^{2+}$ (800 mg/l), $Cu^{2+}$ (600 mg/l), $Pb^{2+}$ (1,100 mg/l), $Cd^{2+}$ (350 mg/l), $ZN^{2+}$ (700 mg/l), and $Fe^{3+}$ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200 mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The $K_m$ values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. $V_{max}$ values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.612-619
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• 2015

We have synthesized gold nanoparticles (GNPs) using chicken feathers (poultry waste) and Bacillus subtilis RSE163. Disulfide reductase and keratinase produced by Bacillus subtilis during the degradation of chicken feather has been used to reduce Au³⁺ from HAuCl₄ precursor to produce gold nanoparticles. The synthesized biogenic GNPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), and zeta potential measurements. Fourier transform infrared (FTIR) spectroscopy indicated the presence of protein capping on synthesized GNPs, imparting multifunctionality to the GNP surface. Furthermore, the nontoxic nature of biogenic GNPs was insured by interaction with Escherichia coli (ATCC11103), where TEM images and enhancement of growth rate of E. coli in log phase signified their nontoxic nature. The results indicate that the synthesis of biocompatible GNPs using poultry waste may find potential applications in drug delivery and sensing.

• Archives of Pharmacal Research
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• v.22 no.6
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• pp.533-541
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• 1999

Many conventional anticancer drugs display relatively poor selectivity for neoplastic cells, in particular for solid tumors. Furthermore, expression or development of drug resistance, increased glutathione transferases as well as enhanced DNA repair decrease the efficacy of these drugs. Research efforts continue to overcome these problems by understanding these mechanisms and by developing more effective anticancer drugs. Cyclophosphamide is one of the most widely used alkylating anticancer agents. Because of its unique activation mechanism, numerous bioreversible prodrugs of phosphramide mustard, the active species of cyclophosphamide, have been investigated in an attempt to improve the therapeutic index. Solid tumors are particularly resistant to radiation and chemotherapy. There has been considerable interest in designing drugs selective for hypoxic environments prevalent in solid tumors. Much of the work had been centered on nitroheterocyclics that utilize nitroreductase enzyme systems for their activation. In this article, recent developments of anticancer prodrug design are described with a particular emphasis on exploitation of selective metabolic processes for their activation.