共查询到20条相似文献,搜索用时 15 毫秒
1.
Izabela Fokt Slawomir Szymanski Stanislaw Skora Marcin Cybulski Timothy Madden Waldemar Priebe 《Carbohydrate research》2009,344(12):340
Modified d-glucose and d-mannose analogs are potentially clinically useful metabolic inhibitors. Biological evaluation of 2-deoxy-2-halo analogs has been impaired by limited availability and lack of efficient methods for their preparation. We have developed practical synthetic approaches to 2-deoxy-2-fluoro-, 2-chloro-2-deoxy-, 2-bromo-2-deoxy-, and 2-deoxy-2-iodo derivatives of d-glucose and d-mannose that exploit electrophilic addition reactions to a commercially available 3,4,6-tri-O-acetyl-d-glucal. 相似文献
2.
d-Hydantoinase and d-carbamoylase genes from Agrobacterium radiobacter TH572 were cloned by polymerase chain reaction (PCR). The plasmid pUCCH3 with a polycistronic structure that is controlled by the native hydantoinase promoter was constructed to co-express the two genes and transformed into Escherichia coli strain JM105. To obtain the highest level of expression of the d-carbamoylase and avoid intermediate accumulation, the d-carbamoylase gene was cloned closer to the promoter and the RBS region in the upstream of it was optimized. This resulted in high active expression of soluble d-hydantoinase and d-carbamoylase that is obtained without any inducer. Thus, by the constitutive recombinant JM105/pUCCH3, d-p-hydroxyphenylglycine (d-HPG) was obtained directly with 95.2% production yield and 96.3% conversion yield. 相似文献
3.
Tomasz Gubica Andrzej Temeriusz Katarzyna Paradowska Andrzej Ostrowski Paulina Klimentowska Micha K. Cyraski 《Carbohydrate research》2009,344(13):1734-1744
The X-ray diffraction patterns, 13C CP MAS NMR spectra, and powder X-ray diffraction analyses were obtained for selected p-nitrophenyl glycosides: α- and β-d-galactopyranosides (1 and 2), α- and β-d-glucopyranosides (3 and 4), and α- and β-d-mannopyranosides (5 and 6). In X-ray diffraction analysis of 1 and 2, characteristic shortening and lengthening of selected bonds were observed in the molecules of 1 due to anomeric effect, and in the crystal lattice of 1 and 2, hydrogen bonds of complex network were detected. In the crystal asymmetric unit of 1 there were two independent molecules, whereas in 2 there was one molecule. For 1 and 3–6 the number of resonances in solid-state 13C NMR spectra exceeded the number of the carbon atoms in the molecules, while for 2 there were distinct singlet resonances in its solid-state NMR spectrum. Furthermore, the powder X-ray diffraction (PXRD) performed for 1–3 and 5 revealed that 1, 3, and 5 existed as single polymorphs proving that the doublets observed in appropriate solid-state NMR spectra were connected with two non-equivalent molecules in the crystal asymmetric unit. On the other hand 2 existed as a mixture of two polymorphs, one of them was almost in agreement with the calculated pattern obtained from XRD (the difference in volumes of the unit cells), and the subsequent unknown polymorph existed in small amounts and therefore it was not observed in solid-state NMR measurements. 相似文献
4.
Evgenija A. Djurendi Marina P. Zavi Marija N. Saka
Jano J. anadi Vesna V. Koji Gordana M. Bogdanovi Katarina M. Penov Gai 《Steroids》2009,74(12):983-988
Starting from 3β-hydroxy-17-oxo-16,17-secoandrost-5-ene-16-nitrile (1), the new 16,17-secoandrostane derivatives 4–9 were synthesized. On the other hand, 3β-hydroxy-17-oxa-d-homoandrost-5-ene-16-one (10) yielded the new d-homo derivatives 12, 13 and 15. In vitro antiproliferative activity of selected compounds against three tumor cell lines (human breast adenocarcinoma ER+, MCF-7, human breast adenocarcinoma ER−, MDA-MB-231, prostate cancer AR−, PC-3, and normal fetal lung fibroblasts, MRC-5) was evaluated. Compounds 3 and 12 showed strong antiproliferative activity against PC-3 cells, the IC50 values being 2 μM and 0.55 μM, respectively. Compounds 6 (10 μM) and 14 (9 μM) showed moderate activity against MDA-MB-231 cells. The synthesized compounds 1–3, 5–8, 10 and 12–15 were not toxic to normal fetal lung fibroblasts cells, MRC-5. 相似文献
5.
An enzyme isolated from Agrobacterium radiobacter was shown to catalyse the following reaction: H2O + N-carbamoyl-d-amino acid→ d-amino acid + NH3 + CO2 Some properties of this new enzyme, N-carbamoyl-d-amino acid amidohydrolase, are presented in this paper. The potential application of this enzyme for the preparation of some d-amino acids used as pharmaceutical intermediates is discussed. 相似文献
6.
Olga N. Solovjeva German A. Kochetov 《Journal of Molecular Catalysis .B, Enzymatic》2008,54(3-4):90-92
An enzymatic method for obtaining d-xylulose 5-phosphate has been developed, based on the irreversible reaction catalyzed by transketolase: hydroxypyruvate + d-glyceraldehyde-3-phosphate → d-xylulose 5-phosphate. The preparations of sodium d-xylulose 5-phosphate, obtained using this approach, were 88% pure and contained no aldehyde admixtures. 相似文献
7.
d-glycero-d-manno-Heptopyranose 7-phosphate—an intermediate in the biosynthesis of nucleotide-activated heptoses—has been prepared in good overall yield from benzyl 5,6-dideoxy-2,3-O-isopropylidene-α-d-lyxo-(Z)-hept-5-enofuranoside by a short-step synthesis. Phosphitylation using the phosphoramidite procedure followed by in situ oxidation afforded the corresponding 7-O-phosphotriester derivative in high yield. Subsequent osmylation proceeded in good diastereoselectivity (4:1) to furnish the d-glycero-d-manno-configured derivative, which was separated from the l-glycero-l-gulo-isomer by chromatography. Hydrogenolysis led to simultaneous removal of the benzyl and isopropylidene groups and afforded the target compound in high yield, which serves as a substrate of bacterial heptose 7-phosphate kinases. 相似文献
8.
Landis W. Doner 《Carbohydrate research》1979,70(2)
Several bases have been evaluated as catalysts for the production of d-psicose (d-ribo-2-hexulose) from d-fructose. The hexose levels in the isomerized mixtures were quantified by l.c. on a μBondapak/Carbohydrate column. The most effective and convenient base was found to be pyridine, and mixtures produced by boiling concentrated solutions (1 g/mL) of d-fructose in pyridine under reflux contained 12.4% of psicose, lesser proportions of glucose and mannose, and 25.8% of the starting material. Following removal of solvent, fermentation with bakers' yeast removed most hexoses other than d-psicose, which was isolated by chromatography on cellulose. The entire procedure required three days, and d-psicose was obtained in gram quantities in 6.8% of the theoretical yield. 相似文献
9.
A general and flexible synthetic approach to biologically important 5,6-unsaturated C18-phytosphingosines was developed via olefin cross-metathesis employing truncated C6-phytosphingosines as the key intermediates. These were efficiently prepared in high yields by zinc-mediated reductive opening of methyl 2-amino-2-deoxy-β-hexopyranosides.
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10.
Jeffrey Cummings Alexander MacLellan Simon P. Langdon Enrique Rozengurt John F. Smyth 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1994,653(2)
n-MePhe8]-substance P(6–11) (G) are currently undergoing preclinical evaluation as potential anticancer agents and clinical trials are planned for G in the near future. A reversed-phase high-performance liquid chromatographic separation has been developed which is both sensitive (limit of detection 250 pg/263 fmol for G; 500 pg/330 fmol for D) and selective, based on electrochemical detection of the two tryptophan residues present in each peptide. Two ion-pairing agents were included in the isocratic mobile phase to eliminate adsorption of the peptides onto the analytical column. Extensive sample clean-up procedures have been developed for plasma, tissue and tumour based on solid-phase extraction. Precision and accuracy of each assay was 91.3 ± 16.9% (between-day) for G and 99.3 ± 16.9% (between-day) for D. The assays were able to detect the intact peptides and a number of their metabolites in plasma, liver and the WX 322 SCLC human xenograft in nude mice for at least 6 hr after administration of therapeutic and pharmacological doses. 相似文献
11.
The Escherichia coli d-xylose isomerase (d-xylose ketol-isomerase, EC 5.3.1.5) gene, xylA, has been cloned on various E. coli plasmids. However, it has been found that high levels of overproduction of the d-xylose isomerase, the protein product of the xylA gene, cannot be accomplished by cloning the intact gene on high copy-number plasmids alone. This is believed to be due to the fact that the expression of the gene through its natural promoter is highly regulated in E. coli. In order to overcome this, the xylA structural gene has been fused with other strong promoters such as tac and lac, resulting in the construction of a number of fused genes. Analysis of the E. coli transformants containing the fused genes, cloned on high copy-number plasmids, indicated that a 20-fold overproduction of the enzyme can now be obtained. It is expected that overproduction of the enzyme in E. coli can still be substantially improved through additional manipulation with recombinant DNA techniques. 相似文献
12.
Juliano M. Andrade Rosa C.D. Peres E.G. Oestreicher O.A.C. Antunes Cludio Dariva 《Journal of Molecular Catalysis .B, Enzymatic》2008,55(3-4):185-188
Polyaniline (PANI) is a water-insoluble polymer that has been used as support for enzyme immobilization due to its desirable characteristics, such as ease of preparation, high synthesis yield, high stability to temperature and pH, and resistance to microbial attack. In this work an investigation was carried out to determine the best conditions to immobilize d-hydantoinase (E.C. 3.5.2.2) in this support. As result, a simple and fast methodology for d-hydantoinase immobilization in PANI is described. 100% of proteins were immobilized on the support in concentrations up to 2 mg solid/ml. Higher concentrations led to a lower protein percentage immobilized. After five reaction cycles about a half of d-hydantoinase initial activity was conserved. 相似文献
13.
14.
The production of d-aminoacylase by Alcaligenes denitrificans and Alcaligenes faecalis has been studied. The enzyme was inducibly produced and N-acetyl-d-leucine and N-acetyl-d-valine were the most effective inducers. d-methionine, d-valine, d-phenylalamine and d-leucine were produced by the enzymic hydrolysis of the appropriate N-acetyl-d-amino-acids with whole cell biomass. The hydrolysis of N-acetyl-d-methionine by A. denitrificans and N-acetyl-d-valine by A. faecalis was preferential. Maximum yields of d-methionine and d-valine were 94.3 and 84.7% at a specific product formation rate of 20.10 and 19.19 μmol min−1 mg−1 of wet cells at 20 mM substrate concentration and 5 mg ml−1 of cell density. 相似文献
15.
d-malate replaced l-malate in supporting both photosynthetic (anaerobic, light) and heterotrophic (aerobic, dark) growth of Rhodopseudomonas capsulata. Growth rates and cell yields were nearly equivalent with both enantiomorphs. Addition of glucose to malate culture media increased the growth rate and doubled the cell yield of heterotrophic cultures, but had little effect on photosynthetic cultures. Aerobically-grown cells showed a higher level of substrate-dependent oxygen uptake with l-malate than with d-malate. This preference for l-malate occured even in cells grown on d-malate. No malic racemase activity was detected in extracts of heterotrophically- or photosynthetically-grown cells. 相似文献
16.
An enzyme has been discovered in Escherichia coli that catalyzes the conversion of the triphosphate ester of 2-amino-4-hydroxy-6-(d-erythro-1′,2′,3′-trihydroxypropyl)-7,8-dihydropteridine, (i.e. d-erythro-dihydroneopterin triphosphate) to an epimer of this compound, l-threo-dihydroneopterin triphophate. The enzyme, which is here named “d-erythro-dihydroneopterin triphosphate 2′-epimerase,” needs a divalent cation (Mg2+ or Mn2+ is most effective) for maximal activity. Its molecular weight is estimated at 87 000–89 000. Little or no activity can be detected if either the monophosphate or the phosphate-free form of the substrate is incubated with the enzyme. Evidence is presented to establish that all three phosphate residues of the substrate are retained in the product and that the product is of the l-threo configuration. 相似文献
17.
Christian Triantaphylides Heinz-Peter Schuchmann Clemens von Sonntag 《Carbohydrate research》1982,100(1)
In the 254-nm photolysis of aqueous solutions of d-fructose, only the openchain form, which is present to an extent of 0.8% in equilibrium with the cyclic forms, absorbs the light. A study of the products and their quantum yields reveals that the main, primary process is C--- bond cleavage α to the carbonyl group. In the absence of oxygen, the subsequent reactions of the resulting radicals are (a) loss of CO from the hydroxyalkylacyl radicals (estimated rate constant a 3 × 106 s−1); (b) consecutive elimination of two molecules of water from the tetritol radicals; and (c) disproportionation and combination reactions. A peculiar products is trans-4-hydroxy-2-butenal, whose precursor is formed from the tetritol radical through elimination of two molecules of water. This compound is a good radical-scavenger and during photolysis quickly attains a low steady-state concentration. One of the products derived from it is a 2,3-dideoxy-2,3-di-C-hydroxymethyltetrose. In the presence of oxygen, the CO elimination process is partly, and the water elimination reactions are fully, suppressed by the fast addition of oxygen to the acylalkyl and hydroxyalkyl radicals. The peroxyl radicals react through unimolecular elimination of HO2 from α-hydroxyalkylperoxyl radicals and bimolecular dismutation with loss of O2, accompanied by loss of CO2 when hydroxyalkylacylperoxyl radicals are involved. 相似文献
18.
Failure of human lymphoid cell lines to grow in d-valine-substituted media is associated with the lack of d-amino acid oxidase activity in these cells. 相似文献
19.
Hiroyuki Nozaki Yasuhiro Takenaka Ikuo Kira Kunihiko Watanabe Kenzo Yokozeki 《Journal of Molecular Catalysis .B, Enzymatic》2005,32(5-6):213-218
Three genes respectively encoding d-specific hydantoinase (DHHase), N-carbamoyl-d-amino acid amidohydrolase (DCHase) and hydantoin racemase (HRase) were co-expressed in E. coli in a system designed for the efficient enzymatic production of d-amino acids via a combination of hydantoin hydrolysis and hydantoin racemization. With the use of whole cells, the d-forms of eight amino acids – d-phenylalanine, d-tyrosine, d-tryptophan, O-benzyl-d-serine, d-valine, d-norvaline, d-leucine and d-norleucine – were efficiently converted from the corresponding dl-5-monosubtituted hydantoin compounds. 相似文献