Transketolase (EC 2.2.1.1, TK) is a thiamine diphosphate-dependent enzyme that catalyzes the transfer of a two-carbon hydroxyacetyl unit with reversible C-C bond cleavage and formation. It is widely used in the production of chemicals, drug precursors, and asymmetric synthesis by cascade enzyme catalysis. In this paper, the activity of transketolase TKTA from Escherichia coli K12 on non-phosphorylated substrates was enhanced through site-directed saturation mutation and combined mutation. On this basis, the synthesis of tartaric semialdehyde was explored. The results showed that the optimal reaction temperature and pH of TKTA_M (R358I/H461S/R520Q) were 32 ℃ and 7.0, respectively. The specific activity on d-glyceraldehyde was (6.57±0.14) U/mg, which was 9.25 times higher than that of the wild type ((0.71±0.02) U/mg). Based on the characterization of TKTA_M, tartaric acid semialdehyde was synthesized with 50 mmol/L 5-keto-d-gluconate and 50 mmol/L non-phosphorylated ethanolaldehyde. The final yield of tartaric acid semialdehyde was 3.71 g with a molar conversion rate of 55.34%. Hence, the results may facilitate the preparation of l-(+)-tartaric acid from biomass, and provide an example for transketolase-catalyzed non-phosphorylated substrates.
Escherichia coli/genetics* ; Transketolase/chemistry* ; Tartrates ; Escherichia coli Proteins/genetics*

The L(+)-form of tartaric acid (L(+)-TA) exists extensively in nature, and is widely used in the food, chemical, textile, building, and pharmaceutical industries (Su et al., 2001). The main method for L(+)-TA production is microbial transformation by cis-epoxysuccinate hydrolase (CESH), which can catalyze the asymmetric hydrolysis of cis-epoxysuccinic acid or its salts to TA or tartrate (Bao et al., 2019). Seventeen species containing CESH have been isolated so far. However, most species for L(+)-TA production have been reported from bacteria (Xuan and Feng, 2019). The only fungus isolated from soil by our lab recently, that could be used as catalyst for the process under acidic condition, is Aspergillus niger WH-2 (Bao et al., 2020). In order to find strains with new characteristics, this study attempted to isolate a new CESH source from fungi and investigate its application value.
Aspergillus niger/metabolism* ; Biomass ; Catalysis ; Fermentation ; Hydrogen-Ion Concentration ; Hydrolases/chemistry* ; Hydrolysis ; Industrial Microbiology ; Magnetic Resonance Spectroscopy ; Penicillium/metabolism* ; Phylogeny ; Soil ; Species Specificity ; Stereoisomerism ; Tartrates/chemistry* ; Temperature ; Textiles

A new composite organic oscillating reaction system based on BrO₃-Ce(SO₄)₂-H₂SO₄-malonic acid/tartaric acid was proposed in this paper. On the basis of the influence of the concentration of each component on the stability and characteristic parameters of the blank system, the electrochemical fingerprints of 30 kinds of traditional Chinese medicines (TCM) were obtained. The results showed that the electrochemical fingerprint can be used for the identification of TCMs, the distinguishment of different parts and the appraisal of genuineness, which is fast, sensitive and accurate. At the same time, we explored and verified the mechanism of oscillation and the formation mechanism of TCM fingerprint.
Drugs, Chinese Herbal ; chemistry ; Electrochemical Techniques ; Malonates ; chemistry ; Medicine, Chinese Traditional ; Phytochemicals ; analysis ; Tartrates ; chemistry

The cis-epoxysuccinate hydrolase (CESH) from Rhizobium strain BK-20 is the key enzyme for L(+)-tartaric acid production. To establish a highly efficient and stable production process, we first optimized the enzyme production from Rhizobium strain BK-20, and then developed an immobilized cell-culture process for sustained production of L(+)-tartaric acid. The enzyme activity of free cells reached (3 498.0 +/- 142.6) U/g, and increased by 643% after optimization. The enzyme activity of immobilized cells reached (2 817.2 +/- 226.7) U/g, under the optimal condition with sodium alginate as carrier, cell concentration at 10% (W/V) and gel concentration at 1.5% (W/V). The immobilized cells preserved high enzyme activity and normal structure after 10 repeated batches. The conversion rate of the substrate was more than 98%, indicating its excellent production stability.
Alginates ; chemistry ; Cells, Immobilized ; Glucuronic Acid ; chemistry ; Hexuronic Acids ; chemistry ; Hydrolases ; metabolism ; Rhizobium ; enzymology ; metabolism ; Tartrates ; metabolism

Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.
Amino Acid Sequence ; Catalytic Domain ; Crystallography, X-Ray ; Humans ; Malonates ; metabolism ; Models, Molecular ; Molecular Sequence Data ; Nitrophenols ; metabolism ; Organophosphorus Compounds ; metabolism ; Phosphoric Monoester Hydrolases ; chemistry ; classification ; metabolism ; Tartrates ; metabolism ; Water ; metabolism

In this study, we prepared various matrices of hydrogel patches and studied their cross-linking mechanism by observing their rheological properties, which could provide theoretical basis and deep technical support for further industrial development of hydrogel patch. Rheology method was used to do the amplitude scanning and single-frequency scanning for various hydrogel matrix, under the condition of oscillation mode of the rheometer. Then the linear viscoelastic region, composite modulus value, as well as changes in slope with time of the composite modulus and phase angle of various hydrogel matrix were analyzed in detail. The results showed that the stability of matrix was mainly determined by hydrogel frame; only in acidic environment, the cross-linking reaction between cross-linker and hydrogel frame can occur; elasticity of matrix can be decreased by organic acid and the effect level was related to the ratio of the number of carboxyl and hydroxyl (-COO(-)/-OH) in adjusters: if the ratio was not equal, the higher -COO(-)/-OH in adjusters would be the less elasticity of matrix decreased; the cross-linking speed of matrix was determined by adjuster, the cross-linking speed of matrix contain different adjusters was ranged in following order: matrix containing tartaric acid > matrix containing lactic acid > matrix containing malic acid > matrix containing citric acid; the cross-linking speed of matrix was not uniform in the whole cross-linking process.
Citric Acid ; chemistry ; Cross-Linking Reagents ; chemistry ; Hydrogels ; chemistry ; Lactic Acid ; chemistry ; Malates ; chemistry ; Rheology ; Tartrates ; chemistry ; Viscosity

The link of hedgehog (Hh) signaling activation to human cancer and synthesis of a variety of Hh signaling inhibitors raise great expectation that inhibiting Hh signaling may be effective in human cancer treatment. Cyclopamine (Cyc), an alkaloid from the Veratrum plant, is a specific natural product inhibitor of the Hh pathway that acts by targeting smoothened (SMO) protein. However, its poor solubility, acid sensitivity, and weak potency relative to other Hh antagonists prevent the clinical development of Cyc as a therapeutic agent. Here, we report properties of cyclopamine tartrate salt (CycT) and its activities in Hh signaling-mediated cancer in vitro and in vivo. Unlike Cyc, CycT is water soluble (5-10 mg/mL). The median lethal dose (LD50) of CycT was 62.5 mg/kg body weight compared to 43.5 mg/kg for Cyc, and the plasma half-life (T1/2) of CycT was not significantly different from that of Cyc. We showed that CycT had a higher inhibitory activity for Hh signaling-dependent motor neuron differentiation than did Cyc (IC50 = 50 nmol/L for CycT vs. 300 nmol/L for Cyc). We also tested the antitumor effectiveness of these Hh inhibitors using two mouse models of basal cell carcinomas (K14cre:Ptch1(neo/neo) and K14cre:SmoM2(YFP)). After topical application of CycT or Cyc daily for 21 days, we found that all CycT-treated mice had tumor shrinkage and decreased expression of Hh target genes. Taken together, we found that CycT is an effective inhibitor of Hh signaling-mediated carcinogenesis.
Animals ; Carcinoma, Basal Cell ; pathology ; Cell Differentiation ; drug effects ; Embryonic Stem Cells ; cytology ; Hedgehog Proteins ; antagonists & inhibitors ; metabolism ; Mice ; Motor Neurons ; cytology ; Plants, Medicinal ; chemistry ; Receptors, G-Protein-Coupled ; antagonists & inhibitors ; metabolism ; Signal Transduction ; drug effects ; Skin Neoplasms ; pathology ; Smoothened Receptor ; Solubility ; Tartrates ; blood ; pharmacology ; Tumor Burden ; drug effects ; Veratrum ; chemistry ; Veratrum Alkaloids ; blood ; isolation & purification ; pharmacology

Vinflunine tartrate-loaded liposomes (VT-L) with two drug-to-lipid ratios were prepared by pH gradient method. Vesicle size and zeta potential were determined by the Zetasizer Nano ZS. Entrapment efficiency was evaluated by cation exchange resin centrifugalization method. The toxicity and tumor inhibition to nude mouse administrated by VT-L with different drug-to-lipid ratios were investigated and compared with the vinflunine tartrate injection (VT-I). The results showed that the mean particle size, zeta potential and entrapment efficiency of the VT-L with drug-to-lipid ratios of 1 : 5 and 1 : 10 were 124.6 nm and 128.3 nm, -25.3 mV and -22.8 mV, 94.46% and 97.31%, respectively. The VT-L with two different drug-to-lipid ratios has significantly higher anti-tumor effect to nude mouse transplanted human non-small cell lung carcinoma A549 and lower toxicity than VT-I. While there were no significant differences in anti-tumor effect and toxicity between VT-L with two different drug-to-lipid ratios.
Animals ; Antineoplastic Agents, Phytogenic ; administration & dosage ; chemistry ; pharmacology ; toxicity ; Cell Line, Tumor ; Drug Carriers ; Drug Compounding ; Drug Delivery Systems ; Drug Stability ; Female ; Humans ; Liposomes ; Lung Neoplasms ; pathology ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Transplantation ; Particle Size ; Random Allocation ; Tartrates ; administration & dosage ; chemistry ; pharmacology ; toxicity ; Tumor Burden ; drug effects ; Vinblastine ; administration & dosage ; analogs & derivatives ; chemistry ; pharmacology ; toxicity

OBJECTIVETo develop an HPLC method for the simultaneous separation and determination of oxalic acid (OA), tartaric acid(TA), malic acid(MA), vitamin C (VC), lactic acid (LA), acetic acid (AA) citric acid (CA) and succinic acid (SA) in Fructus mume.

METHODAnalytical column was Zorbax Eclipse XDB C18. Mobile phase was 0.5% (NH4) H2PO4 aqueous solution and detection wavelength was 214 nm. The flow rate of mobile phase was 0.5 mL x min(-1).

RESULTThe regression equations (pH 2. 8, adjusted with phosphoric acid) of eight constituents have been established, r = 0.999 7, 0. 999 8, 0.999 2, 0.999 6, 0.999 1, 0.999 5, 0.999 8, 0.999 2 respectively. Meanwhile, the content and proportion relationship of eight organic acids in Fructus mume which yielded in Fujian (China) were investigated.

CONCLUSIONThis method was simple, accuracy and quick. The method can be used for the purpose of routine analysis and the quality control of a botanic (Fructus mume) containing these organic acid components.

Acetic Acid ; analysis ; Ascorbic Acid ; analysis ; Carboxylic Acids ; analysis ; Chromatography, High Pressure Liquid ; methods ; Citric Acid ; analysis ; Fruit ; chemistry ; Lactic Acid ; analysis ; Malates ; analysis ; Oxalic Acid ; analysis ; Plants, Medicinal ; chemistry ; Prunus ; chemistry ; Quality Control ; Reproducibility of Results ; Succinic Acid ; analysis ; Tartrates ; analysis

AIMTo establish a resolution method for alpha-cyclohexyl mandelic acid enantiomers by enantioselective extraction and to observe the effects of all kinds of tartaric esters, pH, the concentration of D-tartaric esters and beta-cyclodextrin on the enantioselectivity.

METHODSResolution of alpha-cyclohexyl mandelic acid enantiomers by enantioselective extraction with tartaric esters and beta-cyclodextrin has been studied.

RESULTSThe distribution behavior of alpha-cyclohexyl mandelic acid enantiomers in the separation system was studied. The effects of all kinds of tartaric esters, pH, the concentration of D-tartaric esters and beta-cyclodextrin on the enantioselectivity has been examined in the two-phase.

CONCLUSIONResults showed that the complex formed by D-iso-butyl-D-tartaric ester with R enantiomer is stabler than that with S enantiomer. With the increase of pH, the partition coefficient and separation factor decreased. The concentration of beta-cyclodextrin and D-tartaric ester had visible effect on the enantioselectivity.

Esters ; Mandelic Acids ; chemistry ; Stereoisomerism ; Tartrates ; chemistry ; beta-Cyclodextrins ; chemistry