20246-53-1Relevant articles and documents
Preparation method of gluconic acid
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Paragraph 0009; 0021; 0024-0059, (2019/06/05)
The invention discloses a method for preparing gluconic acid from glucose as a raw material with a catalytic oxidation means. Gluconic acid is prepared through oxidation of glucose by an aqueous phasewith air or oxygen as an oxidizing agent and a transition metal compound and nitrous acid or nitrite as a composite catalyst. The reaction is simple in operation and mild in condition, the glucose conversion rate is high, the selectivity of the gluconic acid product is good, and the method has important application prospects.
Efficient production of sugar-derived aldonic acids by Pseudomonas fragi TCCC11892
Mao, Shuhong,Liu, Yanna,Hou, Yali,Ma, Xiaoyu,Yang, Juanjuan,Han, Haichao,Wu, Jianlin,Jia, Longgang,Qin, Huimin,Lu, Fuping
, p. 39897 - 39901 (2019/01/03)
Aldonic acids are receiving increased interest due to their applications in nanotechnology, food, pharmaceutical and chemical industries. Microbes with aldose-oxidizing activity, rather than purified enzymes, are used for commercial production with limited success. Thus it is still very important to develop new processes using strains with more efficient and novel biocatalytic activities for the production of adonic acids. In the present study, Pseudomonas fragi TCCC11892 was found to be an efficient producer of aldonic acids, with the production of galactonic and l-rhamnonic acid by P. fragi reported for the first time. The semi-continuous production of maltobionic acid and lactobionic acid was developed for P. fragi TCCC11892, achieving a yield of over 90 g L?1 for the first 7 cycles. The excellent performance of P. fragi in the production of lactobionic acid (119 g L?1) was also observed when using waste cheese whey as an inexpensive fermentation medium. Scaling up of the above process for production of aldonic acids with P. fragi TCCC11892 cells should facilitate their commercial applications.
Aqueous oxidation of sugars into sugar acids using hydrotalcite-supported gold nanoparticle catalyst under atmospheric molecular oxygen
Tomar, Ravi,Sharma, Jatin,Nishimura, Shun,Ebitani, Kohki
supporting information, p. 843 - 845 (2016/07/16)
Hydrotalcite-supported gold nanoparticles show good activity as a heterogeneous catalyst for the oxidation of monosaccharides (xylose, ribose, galactose and mannose) and disaccharides (lactose and cellobiose) into the corresponding sugar acids under external base-free conditions in water solvent using atmospheric pressure of molecular oxygen. The produced sugar acids were thoroughly identified by 1H-, 13C-, and HMQC-NMR and ESI-FT-ICR MS spectroscopic techniques.
Selective oxidation of uronic acids into aldaric acids over gold catalyst
Rautiainen, Sari,Lehtinen, Petra,Chen, Jingjing,Vehkam?ki, Marko,Niemel?, Klaus,Leskel?, Markku,Repo, Timo
, p. 19502 - 19507 (2015/04/28)
Herein, uronic acids available from hemicelluloses and pectin were used as raw material for the synthesis of aldaric acids. Au/Al2O3 catalyst oxidized glucuronic and galacturonic acids quantitatively to the corresponding glucaric and galactaric acids at pH 8-10 and 40-60 °C with oxygen as oxidant. The pH has a significant effect on the initial reaction rate as well as desorption of acid from the catalyst surface. At pH 10, a TOF value close to 8000 h-1 was measured for glucuronic acid oxidation. The apparent activation energy Ea for glucuronic acid oxidation is dependent on the pH which can be attributed to the higher energy barrier for desorption of acids at lower pH. This journal is
Hydroxyl radical-induced etching of glutathione-capped gold nanoparticles to oligomeric AuI-thiolate complexes
Chen, Tzu-Heng,Nieh, Chih-Chun,Shih, Ya-Chen,Ke, Chen-Yi,Tseng, Wei-Lung
, p. 45158 - 45164 (2015/06/02)
Thiol-induced core etching of gold nanoparticles is a general method for the production of gold nanoclusters (AuNCs) of various sizes. This paper is the first report on the efficient reaction of glutathione-capped gold nanoparticles (GSH-AuNPs) with hydroxyl radicals to produce oligomeric AuI-thiolate complexes at ambient temperature. Also, hydroxyl radicals can etch commercially available gold nanoparticles (100 nm); this strategy can be applied for the removal of gold from scrap electronics. Additionally, proteins can trigger the aggregation of oligomeric AuI-thiolate complexes under neutral conditions resulting in the formation of fluorescent AuNCs. For example, the reaction of trypsin, lysozyme, and glucose oxidase with oligomeric AuI-thiolate complexes produces Au5, Au8, and Au13 clusters with emission maxima at 415, 460, and 535 nm, respectively. Interestingly, trypsin- and glucose oxidase-stabilized AuNCs could sense GSH and glucose via GSH-induced etching of AuNCs and H2O2-mediated oxidation of AuNCs, respectively. This journal is
Online Investigation of Aqueous-Phase Electrochemical Reactions by Desorption Electrospray Ionization Mass Spectrometry
Lu, Mei,Liu, Yong,Helmy, Roy,Martin, Gary E.,Dewald, Howard D.,Chen, Hao
, p. 1676 - 1685 (2015/09/22)
Electrochemistry (EC) combined with mass spectrometry (MS) is a powerful tool for elucidation of electrochemical reaction mechanisms. However, direct online analysis of electrochemical reaction in aqueous phase was rarely explored. This paper presents the online investigation of several electrochemical reactions with biological relevance in the aqueous phase, such as nitrosothiol reduction, carbohydrate oxidation, and carbamazepine oxidation using desorption electrospray ionization mass spectrometry (DESI-MS). It was found that electroreduction of nitrosothiols [e.g.; nitrosylated insulin B (13-23)] leads to free thiols by loss of NO, as confirmed by online MS analysis for the first time. The characteristic mass shift of 29 Da and the reduced intensity provide a quick way to identify nitrosylated species. Equally importantly, upon collision-induced dissociation (CID), the reduced peptide ion produces more fragment ions than its nitrosylated precursor ion (presumably the backbone fragmentation cannot compete with the facile NO loss for the precursor ion), thus facilitating peptide sequencing. In the case of saccharide oxidation, it was found that glucose undergoes electro-oxidation to produce gluconic acid at alkaline pH, but not at neutral and acidic pHs. Such a pH-dependent electrochemical behavior was also observed for disaccharides such as maltose and cellobiose. Upon electrochemical oxidation, carbamazepine was found to undergo ring contraction and amide bond cleavage, which parallels the oxidative metabolism observed for this drug in leucocytes. The mechanistic information of these redox reactions revealed by EC/DESI-MS would be of value in nitroso-proteome research and carbohydrate/drug metabolic studies.
L-galactose metabolism in bacteroides vulgatus from the human gut microbiota
Hobbs, Merlin Eric,Williams, Howard J.,Hillerich, Brandan,Almo, Steven C.,Raushel, Frank M.
, p. 4661 - 4670 (2014/08/05)
A previously unknown metabolic pathway for the utilization of l-galactose was discovered in a prevalent gut bacterium, Bacteroides vulgatus. The new pathway consists of three previously uncharacterized enzymes that were found to be responsible for the conversion of l-galactose to d-tagaturonate. Bvu0219 (l-galactose dehydrogenase) was determined to oxidize l-galactose to l-galactono-1,5-lactone with kcat and kcat/Km values of 21 s-1 and 2.0 × 105 M-1 s -1, respectively. The kinetic product of Bvu0219 is rapidly converted nonenzymatically to the thermodynamically more stable l-galactono-1,4-lactone. Bvu0220 (l-galactono-1,5-lactonase) hydrolyzes both the kinetic and thermodynamic products of Bvu0219 to l-galactonate. However, l-galactono-1,5-lactone is estimated to be hydrolyzed 300-fold faster than its thermodynamically more stable counterpart, l-galactono-1,4-lactone. In the final step of this pathway, Bvu0222 (l-galactonate dehydrogenase) oxidizes l-galactonate to d-tagaturonate with kcat and kcat/K m values of 0.6 s-1 and 1.7 × 104 M -1 s-1, respectively. In the reverse direction, d-tagaturonate is reduced to l-galactonate with values of kcat and kcat/Km of 90 s-1 and 1.6 × 10 5 M-1 s-1, respectively. d-Tagaturonate is subsequently converted to d-glyceraldehyde and pyruvate through enzymes encoded within the degradation pathway for d-glucuronate and d-galacturonate.
Comparative study of kinetics of catalyzed oxidation of D (+)galactose and lactose by ruthenium (III) in alkaline medium
Kumar, Ashish
, p. 815 - 821 (2013/11/06)
Kinetic investigation in Ru(III) catalyzed oxidation of D(+)-galactose and lactose in an alkaline solution of potassium bromate in the presence of mercuric acetate as a scavenger for Br - ion has been carried out in the temperature range 30-45°C. The rate shows first order dependence with respect to the bromate and zeroth order with respect to the substrate (sugars). The reaction exhibits first order dependence on the catalyst ruthenium(III) and there is inverse order on the rate of reaction. Potassium chloride and acetic acid have a positive effect on the rate. Negligible effect of change in Hg(OAc) 2, ionic strength of the medium and D2O. [RuCl 3(H2O)OH]-1 and BrO3- are the most reactive species Ru(III) chloride and bromated, respectively. Galactonic acid and lactobionic acid have been identified as the main oxidation products of the reaction. Various activation parameters have bee calculated and recorded. On the basis of experimental findings, a suitable mechanism consistent with the observed kinetics was proposed and the rate law has been derived on the basis of obtained data.
Substrate specificity of galactokinase from Streptococcus pneumoniae TIGR4 towards galactose, glucose, and their derivatives
Zou, Yang,Wang, Wenjun,Cai, Li,Chen, Leilei,Xue, Mengyang,Zhang, Xiaomei,Shen, Jie,Chen, Min
supporting information; experimental part, p. 3540 - 3543 (2012/07/03)
Galactokinases (GalKs) have attracted significant research attention for their potential applications in the enzymatic synthesis of unique sugar phosphates. The galactokinase (GalKSpe4) cloned from Streptococcus pneumoniae TIGR4 presents a remarkably broad substrate range including 14 diverse natural and unnatural sugars. TLC and MS studies revealed that GalKSpe4 had relaxed activity towards galactose derivatives with modifications on the C-6, 4- or 2-positions. Additionally, GalKSpe4 can also tolerate glucose while glucose derivatives with modifications on the C-6, 4- or 2-positions were unacceptable. More interestingly, GalKSpe4 can phosphorylate l-mannose in moderate yield (43%), while other l-sugars such as l-Gal cannot be recognized by this enzyme. These results are very significant because there is rarely enzyme reported that can phosphorylate such uncommon substrates as l-mannose.
Electrochemical oxidation of sugars at moderate potentials catalyzed by Rh porphyrins
Yamazaki, Shin-Ichi,Fujiwara, Naoko,Takeda, Sahori,Yasuda, Kazuaki
scheme or table, p. 3607 - 3609 (2010/08/07)
In this communication, we demonstrate that certain kinds of Rh porphyrins on carbon black can electrochemically oxidize aldose at low potentials. The onset potential was much lower than those with the other complex-based catalysts. A product analysis suggested that this reaction involves 2-electron oxidation of the aldehyde group.
