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1.
Komano T Egashira Y Sanada H 《Biochemical and biophysical research communications》2008,372(4):688-690
d-Galactosamine (GalN) induces acute hepatitis in experimental animals and this hepatitis has been shown to be suppressed by preceding ingestion of amino acids such as Gly, l-Ser, and l-Gln. However, little is known about the mechanism of its action. The present study shows for the first time that IL-18 reduction is involved in the suppressive actions of l-Gln and l-Ser on GalN-induced hepatitis. Elevation of IL-18 mRNA expression in liver and its concentration in serum in GalN-treated rats were found to be suppressed by preceding ingestion of 10% l-Gln- or 10% l-Ser diets, and resulted in the attenuation of the increase in serum transaminase (ALT and AST) activities, indexes of hepatic injury. These results suggest that suppressive effects of some dietary amino acids on the GalN-induced hepatitis are mediated by IL-18 reduction. 相似文献
2.
The transport of l-leucine, l-phenylalanine and l-alanine by the perfused lactating rat mammary gland has been examined using a rapid, paired-tracer dilution technique. The clearances of all three amino acids by the mammary gland consisted of a rising phase followed by a rapid fall-off, respectively, reflecting influx and efflux of the radiotracers. The peak clearance of l-leucine was inhibited by BCH (65%) and d-leucine (58%) but not by l-proline. The inhibition of l-leucine clearance by BCH and d-leucine was not additive. l-leucine inhibited the peak clearance of radiolabelled l-leucine by 78%. BCH also inhibited the peak clearance of l-phenylalanine (66%) and l-alanine (33%) by the perfused mammary gland. Lactating rat mammary tissue was found to express both LAT1 and LAT2 mRNA. The results suggest that system L is situated in the basolateral aspect of the lactating rat mammary epithelium and thus probably plays a central role in neutral amino acid uptake from blood. The finding that l-alanine uptake by the gland was inhibited by BCH suggests that LAT2 may make a significant contribution to neutral amino acid uptake by the mammary epithelium. 相似文献
3.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1425-1429
The protective effect of dietary l-glutamine against the hepatotoxic action of d-galactosamine (GalN) was investigated by model experiments with rats. Rats fed with 20% casein diets containing 10% free amino acids were injected with GalN, and the serum aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities and the hepatic glycogen content were assayed 20 hours after the injection. These enzyme activities in the group fed with the 10% l-glutamine diet for 8 days were lower than those in the groups fed with the control, 10% l-glutamic acid and 10% l-alanine diets for 8 days. The more prolonged the feeding period with the 10% l-glutamine diet was, the more the serum activity levels of such enzymes were decreased. Although neomycin also lowered these enzyme activities, its simultaneous ingestion with neomycin did not show any additive or synergistic effect. The hepatic glycogen content in the 10% glutamine group still remained high after the GalN treatment. It is therefore assumed that the effectiveness of glutamine intake would have been mediated by glycogen metabolism rather than by uridine metabolism. 相似文献
4.
Roberts A Bar-Or D Winkler JV Rael LT 《Biochemical and biophysical research communications》2003,304(4):755-757
Epinephrine is known to be rapidly oxidized during sepsis. Ischemia and acidosis, which often accompany sepsis, are associated with the release of weakly bound cupric ions from plasma proteins. We investigated whether copper promotes oxidation of epinephrine at both physiological and acidic pH and whether D-Asp-D-Ala-D-His-D-Lys (D-DAHK), a human albumin (HSA) N-terminus synthetic peptide with a high affinity for cupric ions, attenuates this oxidation. Epinephrine alone [100 microM] or with CuCl(2) [10 microM], and with CuCl(2) [10 microM] and D-DAHK [20 microM] at pH 7.4, 7.0, 6.5, and 6.0 were incubated for 1h at 37 degrees C. Epinephrine oxidation was measured by the spectrophotometric quantification of its oxidation product, adrenochrome. We found that adrenochrome increased, suggesting copper-induced oxidation of epinephrine. At pH 7.4, 7.0, 6.5, and 6.0, adrenochrome increased by 47%, 53%, 24%, and 6% above baseline, respectively. D-DAHK attenuated the copper-induced oxidation of epinephrine to baseline levels. These in vitro results indicate that copper-induced epinephrine oxidation is greatest at the physiological pH 7.4 as well as in severe acidosis, pH 7.0, and that D-DAHK completely inhibits this oxidation. 相似文献
5.
2-Amino-2,3-dideoxy-D-manno-heptonic acid (7) has been synthesized from 2,5,6,7-tetra-O-acetyl-3-deoxy-D-gluco-heptono-1,4-lactone (1), which was readily prepared from D-glycero-D-gulo-heptono-1,4-lactone. O-Deacetylation of 1 followed by treatment with 13:1 (v/v) 2,2-dimethoxypropane/acetone in the presence of p-toluenesulfonic acid gave methyl 3-deoxy-4,5:6,7-di-O-isopropylidene-D-gluco-heptonate (3) as a crystalline product (80% yield). The free hydroxyl group (OH-2) of 3 was mesylated and substituted by azide to give the corresponding azide derivative 5. Hydrogenolysis and further hydrolysis of the ester function of 5 afforded alpha-amino acid 7 (43% overall yield from 1). Compound 7 is an analog of L-alanine having a polyhydroxy chain attached to C-3. The diastereoisomer of 7 at C-2, 2-amino-2,3-dideoxy-D-gluco-heptonic acid (12) was also prepared from 3, by a route that involved 2,3-dideoxy-2-iodo derivative 8 as a key intermediate. 相似文献
6.
Base-catalysed isomerisation of aldoses of the arabino and lyxo series in aluminate solution has been investigated. L-Arabinose and D-galactose give L-erythro-2-pentulose (L-ribulose) and D-lyxo-2-hexulose (D-tagatose), respectively, in good yields, whereas lower reactivity is observed for 6-deoxy-D-galactose (D-fucose). From D-lyxose, D-mannose and 6-deoxy-L-mannose (L-rhamnose) are obtained mixtures of ketoses and C-2 epimeric aldoses. Small amounts of the 3-epimers of the ketoses were also formed. 6-Deoxy-L-arabino-2-hexulose (6-deoxy-L-fructose) and 6-deoxy-L-glucose (L-quinovose) were formed in low yields from 6-deoxy-L-mannose and isolated as their O-isopropylidene derivatives. Explanations of the differences in reactivity and course of the reaction have been suggested on the basis of steric effects. 相似文献
7.
Toukach FV Perepelov AV Bartodziejska B Shashkov AS Blaszczyk A Arbatsky NP Rozalski A Knirel YA 《Carbohydrate research》2003,338(13):1431-1435
The O-polysaccharide of Proteus vulgaris O44, strain PrK 67/57 was studied by 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, ROESY, H-detected 1H, 13C HMQC, HMQC-TOCSY and HMBC experiments. The polysaccharide was found to contain an amide of D-glucuronic acid with L-alanine [D-GlcA6(L-Ala)], and the following structure of the linear pentasaccharide repeating unit was established: [structure: see text]. The structural data of the O-polysaccharide and the results of serological studies with P. vulgaris O44 O-antiserum showed that the strain studied is unique among Proteus bacteria, which is in agreement with its classification in a separate Proteus serogroup, O44. 相似文献
8.
Perepelov AV Zabłotni A Shashkov AS Knirel YA Sidorczyk Z 《Carbohydrate research》2006,341(11):1969-1974
The structure of the O-polysaccharide of Proteus mirabilis CCUG 10705 (OF) was determined by chemical analyses along with one- and two-dimensional (1)H and (13)C NMR spectroscopy. The polysaccharide was found to contain an amide of D-galacturonic acid with L-alanine and based on the uniqueness of the O-polysaccharide structure and serological data, it was suggested to classify P. mirabilis OF into a new separate Proteus serogroup, O74. A weak cross-reactivity of P. mirabilis OF and P. mirabilis O5 was observed and accounted for by a similarity of their O-repeating units. The following structure of the polysaccharide of P. mirabilis OF was established: [chemical structure: see text] 相似文献
9.
Melting behaviour of D-sucrose, D-glucose and D-fructose 总被引:1,自引:0,他引:1
The melting behaviour of d-sucrose, d-glucose and d-fructose was studied. The melting peaks were determined with DSC and the start of decomposition was studied with TG at different rates of heating. In addition, melting points were determined with a melting point apparatus. The samples were identified as d-sucrose, alpha-d-glucopyranose and beta-d-fructopyranose by powder diffraction measurements. There were differences in melting between the different samples of the same sugar and the rate of heating had a remarkable effect on the melting behaviour. For example, T(o), DeltaH(f) and T(i) (initial temperature of decomposition) at a 1 degrees Cmin(-1) rate of heating were 184.5 degrees C, 126.6Jg(-1) and 171.3 degrees C for d-sucrose, 146.5 degrees C, 185.4Jg(-1) and 152.0 degrees C for d-glucose and 112.7 degrees C, 154.1Jg(-1) and 113.9 degrees C for d-fructose. The same parameters at 10 degrees Cmin(-1) rate of heating were 188.9 degrees C, 134.4Jg(-1) and 189.2 degrees C for d-sucrose, 155.2 degrees C, 194.3Jg(-1) and 170.3 degrees C for d-glucose and 125.7 degrees C, 176.7Jg(-1) and 136.8 degrees C d-fructose. At slow rates of heating, there were substantial differences between the different samples of the same sugar. The melting point determination is a sensitive method for the characterization of crystal quality but it cannot be used alone for the identification of sugar samples in all cases. Therefore, the melting point method should be validated for different sugars. 相似文献
10.
Yuji Terami Keiko Uechi Saki Nomura Naoki Okamoto Kenji Morimoto 《Bioscience, biotechnology, and biochemistry》2013,77(10):1725-1729
l-ribose isomerase (L-RI) from Cellulomonas parahominis MB426 can convert l-psicose and d-tagatose to l-allose and d-talose, respectively. Partially purified recombinant L-RI from Escherichia coli JM109 was immobilized on DIAION HPA25L resin and then utilized to produce l-allose and d-talose. Conversion reaction was performed with the reaction mixture containing 10% l-psicose or d-tagatose and immobilized L-RI at 40 °C. At equilibrium state, the yield of l-allose and d-talose was 35.0% and 13.0%, respectively. Immobilized enzyme could convert l-psicose to l-allose without remarkable decrease in the enzyme activity over 7 times use and d-tagatose to d-talose over 37 times use. After separation and concentration, the mixture solution of l-allose and d-talose was concentrated up to 70% and crystallized by keeping at 4 °C. l-Allose and d-talose crystals were collected from the syrup by filtration. The final yield was 23.0% l-allose and 7.30% d-talose that were obtained from l-psicose and d-tagatose, respectively. 相似文献
11.
Sabin C Mitchell EP Pokorná M Gautier C Utille JP Wimmerová M Imberty A 《FEBS letters》2006,580(3):982-987
The lectin from Pseudomonas aeruginosa (PA-IIL) is involved in host recognition and biofilm formation. Lectin not only displays an unusually high affinity for fucose but also binds to L-fucose, L-galactose and D-arabinose that differ only by the group at position 5 of the sugar ring. Isothermal calorimetry experiments provided precise determination of affinity for the three methyl-glycosides and revealed a large enthalpy contribution. The crystal structures of the complexes of PA-IIL with L-galactose and Met-beta-D-arabinoside have been determined and compared with the PA-IIL/fucose complex described previously. A combination of the structures and thermodynamics provided clues for the role of the hydrophobic group in affinity. 相似文献
12.
Erythroascorbic acid (eAsA) is a five-carbon analog of ascorbic acid, and it is synthesized from D-arabinose by D-arabinose dehydrogenase (ARA) and D-arabinono-gamma-lactone oxidase. We found an NAD+-specific ARA activity which is operative under submillimolar level of d-arabinose in the extracts of Saccharomyces cerevisiae. The hypothetical protein encoded by YMR041c showed a significant homology to a l-galactose dehydrogenase which plays in plant ascorbic acid biosynthesis, and we named it as Ara2p. Recombinant Ara2p showed NAD+-specific ARA activity with Km=0.78 mM to d-arabinose, which is 200-fold lower than that for the conventional NADP+-specific ARA, Ara1p. Gene disruptant of ARA2 lost entire NAD+-specific ARA activity and the conspicuous increase in intracellular eAsA by exogenous d-arabinose feeding, while the double knockout mutant of ARA1 and ARA2 still retained measurable amount of eAsA. It demonstrates that Ara2p, not Ara1p, mainly contributes to the production of eAsA from d-arabinose in S. cerevisiae. 相似文献
13.
L-Glutamate in the extracellular space regulates endogenous D-aspartate homeostasis in rat pheochromocytoma MPT1 cells 总被引:1,自引:0,他引:1
Adachi M Koyama H Long Z Sekine M Furuchi T Imai K Nimura N Shimamoto K Nakajima T Homma H 《Archives of biochemistry and biophysics》2004,424(1):89-96
In previous studies [FEBS Lett. 434 (1998) 231, Arch. Biochem. Biophys. 404 (2002) 92], we demonstrated for the first time that D-aspartate (D-Asp) is synthesized in cultured mammalian cell lines, such as pheochromocytoma 12 (PC12) and its subclone, MPT1. Our current focus is analysis of the dynamics of D-Asp homeostasis in these cells. In this communication, we show that L-glutamate (Glu) and L-Glu transporter substrates in the extracellular space regulate the homeostasis of endogenous D-Asp in MPT1 cells. D-Asp is apparently in dynamic homeostasis, whereby endogenous D-Asp is constantly released into the extracellular space by an undefined mechanism, and continuously and intensively taken up into cells by an L-Glu transporter. Under these conditions, L-Glu and its transporter substrates in the medium may competitively inhibit the uptake of D-Asp via the transporter, resulting in accumulation of the amino acid in the extracellular space. We additionally demonstrate that DL-TBOA, a well-established L-Glu transporter inhibitor, is taken up by the transporter during long time intervals, but not on a short time-scale. 相似文献
14.
Six isomeric disaccharides allyl 2,3,5-tri-O-benzoyl-alpha-l-arabinofuranosyl-alpha-d-xylopyranosides and beta-d-xylopyranosides were synthetized by the stereoselective glycosylation of pure allyl alpha- or beta-d-xylopyranosides with 1-O-acetyl-2,3,5-tri-O-benzoyl-l-arabinofuranose as donor, catalyzed with BF(3).Et(2)O in DCM. Regio- and stereoselective glycosylation with excess of donor furnished almost exclusively the trisaccharides allyl 2,3-di-O-(2,3,5-tri-O-benzoyl-alpha-l-arabinofuranosyl)-alpha- or beta-d-xylopyranosides. Extension of the reaction to the triol beta-d-xylopyranosyl-(1-->4)-1,2,3-tri-O-acetyl-alpha-d-xylopyranose, obtained from the 4-hydroxyl penta-O-acetyl-alpha-xylobiose, gave in the same manner the tetrasaccharide [2,3-di-O-(2,3,5-tri-O-benzoyl-alpha-l-arabinofuranosyl)-beta-d-xylopyranosyl]-(1-->4)-1,2,3-tri-O-acetyl-alpha-d-xylopyranose. The protocol described herein should offer the possibility to produce branched oligosaccharides with a 2,3-di-O-(alpha-l-Ara(f))-beta-d-Xyl(p) block unit at the terminal non-reducing end. 相似文献
15.
High doses of diazepam (10.0-20.0 mg/kg) were shown to reduce the volume of acute inflammatory paw edema in rats as a response to carrageenan administration. This effect was attributed to an action of diazepam on the peripheral-type benzodiazepine receptor (PBR) present in the adrenal and/or immune/inflammatory cells. The present study was undertaken to analyze the involvement of nitric oxide (NO) on the effects of diazepam on carrageenan-induced paw edema in rats (CIPE) and to look for the presence of PBR and inducible/constitutive NO synthases (NOS) on slices taken from the inflamed paws of diazepam-treated rats. For that, an acute inhibition of NO biosynthesis was achieved using 50.0 mg/kg No mega-nitro-L-arginine (L-NAME), L-arginine (300.0 mg/kg), the true precursor of NO, and D-arginine (300.0 mg/kg), its false substrate, were also used. The following results were obtained: (1) diazepam (10.0 and 20.0 mg/kg) decreased CIPE values in a dose- and time-dependent way; (2) diazepam effects on CIPE were increased by L-NAME pretreatment; (3) treatment with L-arginine but not with D-arginine reverted at least in part the decrements of CIPE values observed after diazepam administration; (4) PBR were found in endothelial and inflammatory cells that migrated to the inflammatory site at the rat paw; (5) confocal microscopy showed the presence of both PBR and NOS in endothelial and inflammatory cells taken from inflamed paw tissues of rats treated with diazepam a finding not observed in tissues provided from rats treated with diazepam's control solution. These results suggest an important role for NO on the effects of diazepam on CIPE. Most probably, these effects reflect a direct action of diazepam on PBR present in the endothelium of the microvascular ambient and/or on immune/inflammatory cells. An action like that would lead, among other factors, to a decrease in NO, generated by NO synthase, and thus in the mechanisms responsible for CIPE. 相似文献
16.
Giroix MH Scruel O Courtois P Sener A Portha B Malaisse WJ 《Archives of biochemistry and biophysics》2002,408(1):111-123
The metabolism of D-glucose and/or D-fructose was investigated in pancreatic islets from control rats and hereditarily diabetic GK rats. In the case of both D-glucose and D-fructose metabolism, a preferential alteration of oxidative events was observed in islets from GK rats. The generation of 3HOH from D-[5-3H]glucose (or D-[5-3H]fructose) exceeded that from D-[3-3H]glucose (or D-[3-3H]fructose) in both control and GK rats. This difference, which is possibly attributable to a partial escape from glycolysis of tritiated dihydroxyacetone phosphate, was accentuated whenever the rate of glycolysis was decreased, e.g., in the absence of extracellular Ca(2+) or presence of exogenous D-glyceraldehyde. D-Mannoheptulose, which inhibited D-glucose metabolism, exerted only limited effects upon D-fructose metabolism. In the presence of both hexoses, the paired ratio between D-[U-14C]fructose oxidation and D-[3-3H]fructose or D-[5-3H]fructose utilization was considerably increased, this being probably attributable, in part at least, to a preferential stimulation by the aldohexose of mitochondrial oxidative events. Moreover, this coincided with the fact that D-mannoheptulose now severely inhibited the catabolism of D-[5-3H]fructose and D-[U-14C]fructose. The latter situation is consistent with both the knowledge that D-glucose augments D-fructose phosphorylation by glucokinase and the findings that D-mannoheptulose, which fails to affect D-fructose phosphorylation by fructokinase, inhibits the phosphorylation of D-fructose by glucokinase. 相似文献
17.
Synthesis of 4-cyano and 4-nitrophenyl 1,6-dithio-D-manno-, L-ido- and D-glucoseptanosides possessing antithrombotic activity 总被引:1,自引:0,他引:1
1,6-Anhydro-3,4-O-isopropylidene-1-thio-D-mannitol was converted into its sulfoxide which after hydrolysis, acetylation and subsequent Pummerer rearrangement gave the penta-O-acetyl-1-thio-D-mannoseptanose anomers in excellent yield. This anomeric mixture was used as donor for the glycosylation of 4-nitro- and 4-cyanobenzenethiol in the presence of boron trifluoride etherate and trimethylsilyl triflate, respectively, to yield the corresponding thioseptanosides in high yield. The same strategy was applied for the synthesis of the corresponding L-idothioseptanosides using 1,6-anhydro-3,4-O-isopropylidene-1-thio-L-iditol as starting material. The penta-O-acetyl-D-glucothioseptanose donors could not be synthesised the same way, as the Pummerer reaction of the corresponding tetra-O-acetyl-1,6-thioanhydro-1-thio-D-glucitol sulfoxides led to an inseparable mixture of the corresponding L-gulo- and D-glucothioseptanose anomers. Therefore, D-glucose diethyl dithioacetal was converted via its 2,3,4,5-tetra-O-acetyl-6-S-acetyl derivative into an anomeric mixture of its 6-thio-septanose and -furanose peracetates which could be separated by column chromatography. Condensation of the 6-thio-glucoseptanose peracetates with 4-cyano- and 4-nitrobenezenethiol in the presence of boron trifluoride etherate afforded anomeric mixtures of the corresponding thioseptanosides. The D-manno-, L-ido- and D-glucothioseptanosides obtained after Zemplén deacetylation of these mixtures were tested for their oral antithrombotic activity. 相似文献
18.
Different amounts and various types of bis-dinuclear tetradentate molybdate complexes of D-erythro-L-manno-octose, D-erythro-L-gluco-octose, D-erythro-L-manno-octitol and D-erythro-L-gluco-octitol were characterized by 1H and 13C NMR spectroscopy in aqueous solutions. Detailed analysis of 1H-(1)H coupling constants and NOEs, together with chemical shifts, allowed characterization of the different isomers of these complexes. 相似文献
19.
Usvalampi A Turunen O Valjakka J Pastinen O Leisola M Nyyssölä A 《Enzyme and microbial technology》2012,50(1):71-76
l-Xylulose was used as a raw material for the production of l-xylose with a recombinantly produced Escherichia colil-fucose isomerase as the catalyst. The enzyme had a very alkaline pH optimum (over 10.5) and displayed Michaelis-Menten kinetics for l-xylulose with a Km of 41 mM and a Vmax of 0.23 μmol/(mg min). The half-lives determined for the enzyme at 35 °C and at 45 °C were 6 h 50 min and 1 h 31 min, respectively. The reaction equilibrium between l-xylulose and l-xylose was 15:85 at 35 °C and thus favored the formation of l-xylose. Contrary to the l-rhamnose isomerase catalyzed reaction described previously [14]l-lyxose was not detected in the reaction mixture with l-fucose isomerase. Although xylitol acted as an inhibitor of the reaction, even at a high ratio of xylitol to l-xylulose the inhibition did not reach 50%. 相似文献
20.
Kamil Kaminski Ewa Kaminska Patryk Wlodarczyk Jerzy Ziolo Wies?aw Szeja Jerzy Pilch 《Carbohydrate research》2009,344(18):2547-3633
Dielectric relaxation measurements were performed on two enantiomers, d- and l-arabinose and their equimolar mixture, and compared to dielectric data obtained for d-ribose. d-Arabinose differs from d-ribose by having the opposite configuration at C2. This study reveals that both d- and l- of arabinose exhibit α-relaxation peaks with the same shape for the same α-relaxation time τα, and the same steepness index for the Tg-scale T-dependence of τα. However, the two isomers have slightly different glass transition temperatures Tg’s, and their secondary γ-relaxation times also differ slightly from the previously observed γ-relaxation in d-ribose at the same temperature. However, when samples of both investigated monosaccharides are annealed at higher temperatures, their glass transition temperatures become nearly identical. This is an effect of the mutarotation process, which leads to the formation of pairs of the enantiomers and accordingly they should have the same physical properties. The width of the α-relaxation of d- and l-arabinose is broader than that of d-ribose, as reflected by the smaller stretch exponent in the Kohlrausch-Williams-Watts function used to fit the data of the former (βKWW = 0.46 ± 0.01) than the latter (βKWW = 0.55 ± 0.01). The width of the α-relaxation of racemic mixture of the d- and l-arabinose is slightly broader than that of the pure isomers. While the dielectric loss data of d-ribose in the glassy state at ambient and elevated pressures show an inflexion indicating the presence of the JG β-relaxation, the data of d- and l-arabinose show no such feature for identification of the supposedly universal JG β-relaxation. Nevertheless, on comparing the loss spectra of d-arabinose with that of d-ribose, the presence of the JG β-relaxation in d-arabinose has been rationalized. 相似文献