530-26-7Relevant articles and documents
Kinetic and mechanistic study of glucose isomerization using homogeneous organic br?nsted base catalysts in water
Carraher, Jack M.,Fleitman, Chelsea N.,Tessonnier, Jean-Philippe
, p. 3162 - 3173 (2015)
The isomerization of glucose to fructose represents a key intermediate step in the conversion of cellulosic biomass to fuels and renewable platform chemicals, namely, 5-hydroxymethyl furfural (HMF), 2,5-furandicarboxylic acid (FDCA), and levulinic acid (LA). Although both Lewis acids and Br?nsted bases catalyze this reaction, the base-catalyzed pathway received significantly less attention due to its lower selectivity to fructose and the poor yields achieved (1H NMR spectroscopy. Pathways leading to isomerization and degradation of the monosaccharides have been identified through careful experimentation and comparison with previously published data. Kinetic isotope effect experiments were carried out with labeled glucose to validate the rate-limiting step. The ex situ characterization of the reaction products was confirmed using in situ 1H NMR studies. It is shown that unimolecular (thermal) and bimolecular (alkaline) degradation of fructose can be minimized independently by carefully controlling the reaction conditions. Fructose was produced with 32% yield and 64% selectivity within 7 min.
Epicoccamide, a novel secondary metabolite from a jellyfish-derived culture of Epicoccum purpurascens.
Wright, Anthony D,Osterhage, Claudia,Koenig, Gabriele M
, p. 507 - 510 (2003)
From the inner tissue of the jellyfish Aurelia aurita a marine strain of the fungus Epicoccum purpurascens was obtained. After mass cultivation the fungus was investigated for its secondary metabolite content and found to contain the new, and most unusual tetramic acid derivative, epicoccamide (1). Epicoccamide is quite unusual since it is composed of three biosynthetically distinct subunits; glycosidic, fatty acid and tetramic acid (amino acid). The structure of the new compound was elucidated using spectroscopic methods, mainly 1D and 2D NMR, ESI-MS, and chemical degradations.
Purification and characterization of α-D-mannosidase from the seeds of Kaya, Torreya nucifera
Shikoo, Tomomi,Ohtani, Kimiko,Huchigami, Kyoko,Nakatani, Masato,Yuasa, Isao,Misaki, Akira
, p. 687 - 688 (1996)
Alpha-D-mannosidase was purified from the extract of seeds of Kaya, Torreya nucifera. The purified enzyme had a molecular mass of ～ 3.6 × 105 daltons. This enzyme had an optimum pH at 4.5, and was stable at pH between 5.5 and 6.5. This enzyme appeared to be a metal enzyme containing Zn2-. The enzyme hydrolyzed p-nitrophenyl-α-D-mannoside, methyl-α-D-mannoside, α-1-→3-mannobiose, and α-1-→6-mannobiose, with Km of 0.785 mM, 0.236 M, 2.505 mM, and 0.268 mM, respectively. The hydrolysis of various α-linked mannobioses indicated that the enzyme hydrolyzes the α-mannobioses in the order of α-(1→2)> -(1→6)> -(1→3).
C-2 Epimerization of Aldoses Promoted by Combination of Monoamines and Alkaline Earth or Rare Earth Metal Ions, Involving a Rearrangement of the Carbon Skeleton
Tanase, Tomoaki,Murata, Takashi,Yano, Shigenobu,Hidai, Masanobu,Yoshikawa, Sadao
, p. 1409 - 1412 (1987)
Aldoses are rapidly epimerized at C-2 by combination of alkaline earth or rare earth metal ions (Ca2+, Sr2+,Pr3+, or Ce3+)and monoamines (triethlamine etc.). (13)C NMR studies using -D-glucose of the Ca2+ system revealed that this reaction proceeds via the stereospecific rearrangement of carbon skeleton.
Chemical constituents and antioxidant, anti-inflammatory and anti-tumor activities of melilotus officinalis (linn.) pall
Liu, Yu-Ting,Gong, Pei-Han,Xiao, Feng-Qin,Shao, Shuai,Zhao, Da-Qing,Yan, Ming-Ming,Yang, Xiu-Wei
, (2018)
Two new p-hydroxybenzoic acid glycosides, namely p-hydroxybenzoic acid-4-O-α-D-manopyranosyl-(1 → 3)-α-L-rhamnopyranoside (compound 1) and 4-O-α-L-rhamnopyran-osyl-(1 → 6)-α-D-manopyranosyl-(1 → 3)-α-L-rhamnopyranoside (compound 2), and seven known compounds, compound 3, 6, 7 (acid components), compound 8, 9 (flavonoids), compound 4 (a coumarin) and compound 5 (an alkaloid), were isolated from the 70% ethanol aqueous extract of the aerial parts of Melilotus officinalis (Linn.) Pall. The structures of all compounds were elucidated by use of extensive spectroscopic methods Infrared Spectroscopy (IR), High resolution electrospray ionization mass spectrometry (HR-ESI-MS), and1H and13C-NMR). Sugar residues obtained after acid hydrolysis were identified by high-performance liquid chromatography (HPLC). The antioxidant activity of all the compounds was evaluated by 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The anti-inflammatory effects of the compounds were also evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. All compounds were shown to inhibit LPS-induced nitric oxide (NO) and prostaglandin E 2 (PGE 2) production by suppressing the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), respectively, in LPS-stimulated RAW 264.7 cells. The inhibitory effect of all the compounds on MCF-7 cells was determined by Cell Counting Kit-8 (CCK-8) method. The results showed that compounds 1, 2, 7, 8, 9 exhibited better antioxidant activity compared to the other compounds. compounds 1–9 had different inhibitory effects on the release of NO, TNF-α and IL-6 in LPS-stimulated RAW264.7 cells by LPS, of which compound 7 was the most effective against inflammatory factors. compounds 1 and 2 have better antitumor activity compared to other compounds. Further research to elucidate the chemical composition and pharmacological effects of Melilotus officinalis (Linn.) Pall is of major importance towards the development and foundation of clinical application of the species.
Biochemical characterization of a recombinant acid phosphatase from Acinetobacter baumannii
Smiley-Moreno, Elizabeth,Smith, Douglas,Yu, Jieh-Juen,Cao, Phuong,Arulanandam, Bernard P.,Chambers, James P.
, (2021/06/09)
Genomic sequence analysis of Acinetobacter baumannii revealed the presence of a putative Acid Phosphatase (AcpA; EC 3.1.3.2). A plasmid construct was made, and recombinant protein (rAcpA) was expressed in E. coli. PAGE analysis (carried out under denaturing/ reducing conditions) of nickel-affinity purified protein revealed the presence of a nearhomogeneous band of approximately 37 kDa. The identity of the 37 kDa species was verified as rAcpA by proteomic analysis with a molecular mass of 34.6 kDa from the deduced sequence. The dependence of substrate hydrolysis on pH was broad with an optimum observed at 6.0. Kinetic analysis revealed relatively high affinity for PNPP (Km = 90 μM) with Vmax, kcat, and Kcat/Km values of 19.2 pmoles s-1, 4.80 s-1(calculated on the basis of 37 kDa), and 5.30 × 104 M-1s-1, respectively. Sensitivity to a variety of reagents, i.e., detergents, reducing, and chelating agents as well as classic acid phosphatase inhibitors was examined in addition to assessment of hydrolysis of a number of phosphorylated compounds. Removal of phosphate from different phosphorylated compounds is supportive of broad, i.e., 'nonspecific' substrate specificity; although, the enzyme appears to prefer phosphotyrosine and/or peptides containing phosphotyrosine in comparison to serine and threonine. Examination of the primary sequence indicated the absence of signature sequences characteristic of Type A, B, and C nonspecific bacterial acid phosphatases.
Tuning Ca-Al-based catalysts' composition to isomerize or epimerize glucose and other sugars
Ventura, Maria,Cecilia, Juan A.,Rodríguez-Castellón, Enrique,Domine, Marcelo E.
, p. 1393 - 1405 (2020/03/11)
One of the key reactions to achieve good productivity in the transformations of cellulose derived from biomass feedstocks is the isomerization of glucose to fructose, the latest being the platform molecule for obtaining other important derivatives. In this work, Ca-Al containing catalysts based on hydrotalcite-type derived materials were used to perform the selective isomerization of glucose to fructose, and the selective epimerization of glucose to mannose, using water as the solvent under mild reaction conditions. The catalysts showed high activity (conversion = 51-87%), and excellent selectivity (63-88%) towards fructose, compared with the current industrial process based on the glucose transformation via biocatalysis. It was also possible to modulate the selectivity towards fructose or mannose by tuning the amount of basic sites of the catalysts and their composition. The combination of basic and acid sites present in the Ca-Al-based catalysts plays a key role in the reaction, a fact that is discussed in the text together with other important operational parameters. The stability and recyclability of the catalysts were tested, detecting only a small activity loss after 5 consecutive runs. The synthesis of the catalysts and their characterization are also discussed since they are one of the few cases found in the literature of this kind of hydrotalcite-type material with such a high level of Ca incorporation. Some green metrics, such as E-factor, have been calculated to evaluate our system as an environmentally friendly process.
