EC Number   |
Protein Variants |
Reference |
|---|
   1.1.1.B20 | D194G |
site-directed mutagenesis, the mutant binds the substrate but is catalytically almost inactive. The mutant is inactive with (2S,3S)-butanediol, meso-butanediol and (2R,3R)-butanediol. D194G enzyme mutant shows a similar secondary structure compared to Enterobacter aerogenes BDH. While the mutant is highly susceptible to protease digestion compared to the wild-type enzyme. Homology modeling of the mutant enzyme, with meso-2,3-butanediol dehydrogenase from Klebsiella pneumoniae, PDB ID 1GEG, as a template, reveals that Gly194 seems to lose the hydrogen bond interactions with the surrounding residues (Gly206, Gly207 and Thr209), resulting in a putative conformational changes of mutant D194G which might be responsible for the loss of activity |
743096 |
| 1.1.1.B20 | F212S |
site-directed mutagenesis, the mutant shows highly reduced activity compared to wild-type |
761081 |
| 1.1.1.B20 | F212W |
site-directed mutagenesis, the mutant shows reduced activity compared to wild-type |
761081 |
| 1.1.1.B20 | F212Y |
site-directed mutagenesis, the kcat of the mutant is enhanced 4-8fold compared to wild-type |
761081 |
| 1.1.1.B20 | moe |
construction and engineering of Corynebacterium glutamicum strain DELTAaceEDELTApqoDELTAldhA(pEKEx2-als,aldB,butACg). Chromosomal inactivation of the putative BDH gene butACg (cg2958) in strain DELTAaceEDELTApqoDELTAldhA. BDH activity is nearly abolished upon inactivation of butACg indicating that Corynebacterium glutamicum expresses a single BDH under the experimental conditions examined. BDH activity increases 3fold in strain DELTAaceEDELTApqoDELTAldhA(pEKEx2-als,aldB,butACg) compared to the respective control. The inactivation of butACg gene decreases the BDH activity 75fold for the DELTAaceEDELTApqoDELTAldhADELTAbutACg(pEKEx2) strain compared to strain DELTAaceEDELTApqoDELTAldhA(pEKEx2). The major form of 2,3-butanediol is meso-2,3-butandediol, and the ratio meso-2,3-BD/optically active 2,3-BD is 95:5, the main side products are glycerol, ethanol, and acetoin |
741710 |
| 1.1.1.B20 | more |
a two-enzyme system composed of meso-2,3-butanediol dehydrogenase (BDH) and xylose reductase (CT-XR) from Candida tenuis is constructed to co-produce acetoin and xylitol with NAD+ regeneration. Four BDHs from four candidate organisms (Bacillus subtilis, Corynebacterium glutamicum, Parageobacillus thermoglucosidans, and Pyrococcus furiosus), as well as xylose reductase from Candida tenuis are purified and analyzed The best BDH is then selected according to titers and chiral purities of acetoin. After optimization of reaction conditions, and the ratios of meso-2,3-butanediol to xylose and BDH to xylose reductase, 28.5 g/l D-(-)-acetoin with an optical purity of 95.2% is produced in 6 h. The yield and productivity of acetoin is 0.97 g/g and 4.75 g/l/h. The titer of co-product xylitol is 40.29 g/l, and the yield and productivity of xylitol reaches 0.98 g/g and 6.72 g/l/h. Method development, evaluation, and optimization for production of optically pure D-(-)-acetoin, overview. Enzyme CT-XR acts most effectively with BDH from Corynebacterium glutamicum (CG-BDH) |
-, 761599 |
| 1.1.1.B20 | more |
Bacillus subtilis is engineered to produce chiral pure meso-2,3-BD. D-2,3-butanediol production is abolished by deleting D-2,3-butanediol dehydrogenase (EC 1.1.1.4) coding gene bdhA, and acoA gene is knocked out to prevent the degradation of acetoin, the immediate precursor of 2,3-butanediol. Next, both pta and ldh gene are deleted to decrease the accumulation of the byproducts, acetate and L-lactate. The meso-2,3-butanediol dehydrogenase coding gene from Klebsiella pneumoniae CICC10011 is introduced, as well as alsSD overexpressed in the tetra mutant (DELTAacoADELTAbdhADELTAptaDELTAldh) to achieve the efficient production of chiral meso-2,3-butanediol. Finally, the pool of NADH availability is further increased to facilitate the conversion of meso-2,3-butanediol from acetoin by overexpressing the udhA gene (coding a soluble transhydrogenase) and low dissolved oxygen control during the cultivation. Under microaerobic oxygen conditions, the best strain BSF9 produced 103.7 g/L meso-2,3-butanediol with a yield of 0.487 g/g glucose in the 5-L batch fermenter, and the titer of the main byproduct acetoin is no more than 1.1 g/L. Method optimization. The titer of meso-2,3-butanediol is almost unchanged at 37°C, 42°C, and 46°C, while the meso-2,3-butanediol productivity increases when the cultivation temperature is increased from 37°C to 46°C. The titer and productivity at 50°C decreases by 28.6% and 36.3% compared to those at 37°C |
-, 742158 |
| 1.1.1.B20 | more |
chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) is obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX), and hemoglobin protein (VHB) from Serratia sp. T241, Lactobacillus brevis, and Vitreoscilla, respectively. The biocatalysis system of Escherichia coli/pET-mbdh-nox-vgb is developed and the bioconversion conditions are optimized. Under the optimal conditions, 86.74 g/l of (3R)-acetoin with the productivity of 3.61 g/l/h and the stereoisomeric purity of 97.89% is achieved from 93.73 g/l meso-2,3-BD using the whole-cell biocatalysis system, pH 7.0 at 30°C for 12 h. The results show the industrial potential for (3R)-acetoin production via whole-cell biocatalysis. Escherichia coli/pET-mbdh cannot produce acetoin from (2R,3R)-2,3-BD as substrate. To obtain high (3R)-acetoin productivity, a cofactor regeneration system involved in co-expression of meso-2,3-BDH and NOX enzymes from Serratia sp. T241 Lactobacillus brevis is developed in Escherichia coli. The NOX enzyme efficiently oxidizes NADH, which is formed by meso-2,3-BDH, and regenerate NAD+ for the biocatalytic process. The feasibility of (3R)-AC production from the substrate of meso-2,3-BD by whole-cell biocatalysis is conducted, method optimization, overview. A small amount of (3S)-acetoin (1.86 g/l) can also be produced from (2S,3S)-2,3-BD in the substrate 2,3-BD (2.23% of (2S,3S)-2,3-BD) by the biocatalyst |
743082 |
| 1.1.1.B20 | more |
construction of a knockout Bacillus licheniformis mutant DELTAbudCDELTAgdh deleting two 2,3-butanediol dehydrogenases, i.e. meso-2,3-butanediol dehydrogenases BudC and GDH, through gene disruption. Escherichia coli strain S17-1 lpir is used as donor strain to allow the conjugal transfer of plasmids pKVM1-1budC and pKVM1-1gdh into Bacillus licheniformis strain MW3. Although the growth of strain MW3 (DELTAbudCDELTAgdh) is slightly lower than that of wild-type strain MW3, it can produce acetoin instead of 2,3-butanediol as its major product. Using fedbatch fermentation of Bacillus licheniformis MW3 (DELTAbudCDELTAgdh), 64.2 g/l acetoin is produced at a productivity of 2.378 g/l/h and a yield of 0.412 g/g from 156 g/l glucose in 27 h |
-, 761121 |
| 1.1.1.B20 | more |
construction of an engineered Bacillus subtilis strain 168 in which the bdhA gene is knocked out by the cre/lox system using the lox71-zeo-lox66 resistance marker cassette. The effects of bdhA gene deletion on production of acetoin and 2,3-butanediol are evaluated. By increasing the glucose concentration, the acetoin yield is improved from 6.61 g/l to 24.6 g/l. Deletion of the gene bdhA efficiently blocks the transformation of acetoin and 2,3-butanediol during the fermentation of strain BS168D, overview |
-, 762259 |
