Hideshi Yanase

Stereoselective reduction of ethyl 4-chloro-3-oxobutanoate by Escherichia coli transformant cells coexpressing the aldehyde reductase and glucose dehydrogenase genes

Abstract The asymmetric reduction of ethyl 4-chloro-3-oxobutanoate (COBE) to ethyl (R)-4-chloro-3-hydroxybutanoate [(R)-CHBE] using Escherichia coli cells, which coexpress both the aldehyde reductase gene from Sporobolomyces salmonicolor and the glucose dehydrogenase (GDH) gene from Bacillus megaterium as a catalyst was investigated. In an organic solvent-water two-phase system, (R)-CHBE formed in the organic phase amounted to 1610 mM (268 mg/ml), with a molar yield of 94.1% and an optical purity of 91.7% enantiomeric excess. The calculated turnover number of NADP+ to CHBE formed was 13 500 mol/mol. Since the use of E. coli JM109 cells harboring pKAR and pACGD as a catalyst is simple, and does not require the addition of GDH or the isolation of the enzymes, it is highly advantageous for the practical synthesis of (R)-CHBE.

Enzymatic production of ethyl (R )-4-chloro-3-hydroxybutanoate: asymmetric reduction of ethyl 4-chloro-3-oxobutanoate by an Escherichia coli transformant expressing the aldehyde reductase gene from yeast

Abstract The asymmetric reduction of ethyl 4-chloro-3-oxobutanoate (COBE) to ethyl (R)-4-chloro-3-hydroxybutanoate (CHBE) using Escherichia coli JM109 (pKAR) cells expressing the aldehyde reductase gene from Sporobolomyces salmonicolor AKU4429 as a catalyst was studied. The reduction required NADP+, glucose and glucose dehydrogenase for NADPH regeneration. In an aqueous system, the substrate was unstable, and inhibition of the reaction by the substrate was also observed. Efficient conversion of COBE to (R)-CHBE with a satisfactory enantiomeric excess (ee) was attained on incubation with transformant cells in an n-butyl acetate/water two-phase system containing the above NADPH-regeneration system. Under the optimized conditions, with the periodical addition of COBE, glucose and glucose dehydrogenase, the (R)-CHBE yield reached 1530 mM (255 mg/ml) in the organic phase, with a molar conversion yield of 91.1% and an optical purity of 91% ee. The calculated turnover of NADP+, based on the amounts of NADP+ added and CHBE formed, was about 5100 mol/mol.

Ethanol production from cellulosic materials by genetically engineered Zymomonas mobilis

AbstractTo confer the ability to ferment cello-oligosaccharides on the ethanol-producing bacterium, Zymomonas mobilis, the β-glucosidase gene from EmRuminococcus albus, tagged at its N-terminal with the 53-amino acid Tat signal peptide from the periplasmic enzyme glucose–fructose oxidoreductase from Z. mobilis, was introduced into the strain. The tag enabled 61% of the β-glucosidase activity to be transported through the cytoplasmic membrane of the recombinant strain which then produced 0.49 g ethanol/g cellobiose.

Degradation of the metal-cyano complex tetracyanonickelate (II) by Fusarium oxysporum N-10

Abstract A fungus with the ability to utilize a metal-cyano compound, tetracyanonickelate (II) {K2[Ni (CN)4]; TCN}, as its sole source of nitrogen was isolated from soil and identified as Fusarium oxysporum N-10. Both intact mycelia and cell-free extract of the strain catalyzed hydrolysis of TCN to formate and ammonia and produced formamide as an intermediate, thereby indicating that a hydratase and an amidase sequentially participated in the degradation of TCN. The enzyme catalyzing the hydration of TCN was purified approximately ten-fold from the cell-free extract of strain N-10 with a yield of 29%. The molecular mass of the active enzyme was estimated to be 160 kDa. The enzyme appears to exist as a homotetramer, each subunit having a molecular mass of 40 kDa. The enzyme also catalyzed the hydration of KCN, with a cyanide-hydrating activity 2 × 104 times greater than for TCN. The kinetic parameters for TCN and KCN indicated that hydratase isolated from F. oxysporum was a cyanide hydratase able to utilize a broad range of cyano compounds and nitriles as substrates.

Cloning, Sequencing, and Characterization of the Intracellular Invertase Gene from Zymomonas mobilis

The structural gene for the intracellular invertase E1 of Zymomonas mobilis strain Z6C was cloned in a 2.25-kb DNA fragment on pUSH11, and expressed in Escherichia coli HB101. The enzyme produced by the E. coli carrying pUSH11 was purified about 1,122 fold to homogenicity with a yield of 4%. The molecular weight and substrate specificity of the enzyme were identical with those of the intracellular invertase E1 from Z. mobilis. The nucleotides of the cloned DNA were sequenced; they included an open reading frame of 1,536 bp, coding for a protein with a molecular weight of 58,728. The N-terminal amino acid sequence predicted was identical with the sequence of the first 20 N-terminal amino acid residues of the protein obtained by Edman degradation. Comparison of the predicted amino acid sequence of E1 protein with those of the four other known beta-D-fructofuranosidases from Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae indicated a stronger homology in the N-terminal portion than in the C-terminal portion.

Peroxygenase-Catalyzed Oxyfunctionalization Reactions Promoted by the Complete Oxidation of Methanol

Peroxygenases catalyze a broad range of (stereo)selective oxyfunctionalization reactions. However, to access their full catalytic potential, peroxygenases need a balanced provision of hydrogen peroxide to achieve high catalytic activity while minimizing oxidative inactivation. Herein, we report an enzymatic cascade process that employs methanol as a sacrificial electron donor for the reductive activation of molecular oxygen. Full oxidation of methanol is achieved, generating three equivalents of hydrogen peroxide that can be used completely for the stereoselective hydroxylation of ethylbenzene as a model reaction. Overall we propose and demonstrate an atom-efficient and easily applicable alternative to established hydrogen peroxide generation methods, which enables the efficient use of peroxygenases for oxyfunctionalization reactions.

Cloning of poly(3-hydroxybutyrate) depolymerase from a marine bacterium, Alcaligenes faecalis AE122, and characterization of its gene product

A DNA fragment that carries the gene coding for poly(3-hydroxybutyrate) (PHB) depolymerase was cloned from the chromosomal DNA of Alcaligenes faecalis AE122 isolated from seawater. The open reading frame encoding the precursor of the PHB depolymerase was 1905 base pairs (bp) long, corresponding to a protein of 635 amino acid residues (M(r) = 65,208). The promoter site, which could be recognized by Escherichia coli RNA polymerase, was upstream from the gene, and the sequence adhering to the ribosome-binding sequence was found in front of the gene. The deduced amino acid sequence agreed with the N-terminal amino acid sequence of the purified PHB depolymerase from amino acid 28 onwards. Analysis of the deduced amino acid sequence revealed the domain structure of the protein; a signal peptide of 27 amino acids long was followed by a catalytic domain of about 400 amino acids, a fibronectin type III module sequence, and a putative substrate binding domain. The molecular mass (62,526) of the mature protein deduced from the nucleotide sequence was significantly lower than the value (95 kDa) estimated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but coincided well with the value (62,426) estimated from matrix-assisted laser desorption ionization mass spectra. By comparison of the primary structure with those of other PHB depolymerases, the substrate binding domain was found to consist of two domains, PHB-specific and poly(3-hydroxyvalerate)-specific ones, connected by a linker region. The PHB depolymerase gene was expressed in Escherichia coli under the control of the tac promoter. The enzyme expressed in E. coli was purified from culture broth and showed the same catalytic properties as the enzyme from A. faecalis.

Purification and characterization of new aldehyde reductases from Sporobolomyces salmonicolor AKU4429

Abstract New aldehyde reductases (AR), ARII and ARIII, which reduce ethyl 4-chloro-3-oxobutanoate (4-COBE) to ethyl 4-chloro-3-hydroxybutanoate (CHBE), with NADPH as a cofactor, were purified from Sporobolomyces salmonicolor AKU4429. The two enzymes were different from another aldehyde reductase (ARI) which had already been purified and characterized [Yamada et al., FEMS Microbiol. Lett., 70 (1990) 45; Kataoka et al., Biochim. Biophys. Acta, 1122 (1992) 57]. ARII catalyzed the stereospecific reduction of 4-COBE to (S)-CHBE (92.7% enantiomeric excess (e.e.)). In contrast, ARIII reduced 4-COBE to (R)-CHBE (38.4% e.e.). ARII was characterized further, and reduced aliphatic and aromatic aldehydes, as well as carbonyl compounds, such as camphorquinone, but did not accept aldose as a substrate. The enzyme is a monomer protein with a relative molecular mass of 34,000. Its isoelectric point is 5.0. The NH2-terminal amino acid sequence of ARII is different from that of ARI, which catalyzes the stereospecific reduction of 4-COBE to (R)-CHBE (100% e.e.).

Isolation and application of a styrene-degrading strain of Pseudomonas putida to Biofiltration

A bacterial strain ST201 capable of degrading styrene was isolated from soil and identified as Pseudomonas putida. This strain had high tolerance to styrene and could degrade it completely in 48 h at concentrations up to 600 mg/l. P. putida ST201 was also demonstrated to degrade a mixture of benzene, toluene, ethylbenzene and p-xylene. A packed tower biofilter inoculated with P. putida ST201 was constructed which removed styrene vapor with a styrene elimination capacity of 90 g/m3.h.

Degradation of phenols by thermophilic and halophilic bacteria isolated from a marine brine sample

Abstract Two thermophilic bacteria that degrade phenol, strains 401 and 501, were isolated from a brine sample from a submarine gas field. Strain 401 was identified as being Bacillus stearothermophilus. Strain 501 was tentatively identified as a previously unknown species in the family of Rhizobiaceae. Strains 401 and 501 completely degraded phenol at the concentrations of 1,000 and 700 mg/l, respectively, while growing on a nutrient broth at 50°C. Bacterial cells grown on a medium containing phenol degraded a variety of phenolic compounds. Strain 401 tolerated up to 10% NaCl, and strain 501 absolutely required seawater for growth and phenol degradation. Such thermophilic bacteria that tolerate salt and phenol might be useful for the treatment of industrial wastes containing phenols.