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Cellular & Molecular Immunology Oct 2020
Topics: Animals; Cell Polarity; Galactose; Humans; Inflammation; Macrophages; Phenotype
PubMed: 31900455
DOI: 10.1038/s41423-019-0358-2 -
Bioengineered Dec 2021β-galactosidase catalyzes lactose hydrolysis and transfers reactions to produce prebiotics such as galacto-oligosaccharides (GOS) with potential applications in the...
β-galactosidase catalyzes lactose hydrolysis and transfers reactions to produce prebiotics such as galacto-oligosaccharides (GOS) with potential applications in the food industry and pharmaceuticals. However, there is still a need for improved transgalactosylation activity of β-galactosidases and reaction conditions of GOS production in order to maximize GOS output and reduce production costs. In this study, a β-galactosidase gene, , from was expressed in , which not only hydrolyzed lactose but also had strong transgalactosylation activity to produce GOS. Response surface methodology was adopted to investigate the effects of temperature, enzyme concentration, pH, initial lactose concentration, and reaction time on the production of GOS and optimize the reaction conditions for GOS. The optimal pH for the enzyme was 6.0 and remained stable under neutral and basic conditions. Meanwhile, GALA showed most activity at 50°C and retained considerable activity at a lower temperature 30-40°C, indicating this enzyme could work under mild conditions. The enzyme concentration and temperature were found to be the critical parameters affecting the transgalactosylation activity. Response surface methodology showed that the optimal enzyme concentration, initial lactose concentration, temperature, pH, and reaction time were 3.03 U/mL, 500 g/L, 30°C, 5.08, and 4 h, respectively. Under such conditions, the maximum yield of GOS was 252.8 g/L, accounting for approximately 50.56% of the total sugar. This yield can be considered relatively high compared to those obtained from other sources of β-galactosidases, implying a great potential for GALA in the industrial production and application of GOS.
Topics: Bacillus; Bacterial Proteins; Galactose; Hydrogen-Ion Concentration; Kinetics; Temperature; beta-Galactosidase
PubMed: 34606421
DOI: 10.1080/21655979.2021.1988370 -
The Journal of Biological Chemistry Jan 1957
Topics: Brain; Galactose; Lipids; Neurochemistry
PubMed: 13398425
DOI: No ID Found -
Molecules (Basel, Switzerland) Jan 2023Eight novel carbohydrate-tethered trithiolato dinuclear ruthenium(II)-arene complexes were synthesized using CuAAC ‘click’ (Cu(I)-catalyzed azide-alkyne...
Eight novel carbohydrate-tethered trithiolato dinuclear ruthenium(II)-arene complexes were synthesized using CuAAC ‘click’ (Cu(I)-catalyzed azide-alkyne cycloaddition) reactions, and there in vitro activity against transgenic T. gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) and in non-infected human foreskin fibroblasts, HFF, was determined at 0.1 and 1 µM. When evaluated at 1 µM, seven diruthenium-carbohydrate conjugates strongly impaired parasite proliferation by >90%, while HFF viability was retained at 50% or more, and they were further subjected to the half-maximal inhibitory concentration (IC50) measurement on T. gondii β-gal. Results revealed that the biological activity of the hybrids was influenced both by the nature of the carbohydrate (glucose vs. galactose) appended on ruthenium complex and the type/length of the linker between the two units. 23 and 26, two galactose-based diruthenium conjugates, exhibited low IC50 values and reduced effect on HFF viability when applied at 2.5 µM (23: IC50 = 0.032 µM/HFF viability 92% and 26: IC50 = 0.153 µM/HFF viability 97%). Remarkably, compounds 23 and 26 performed significantly better than the corresponding carbohydrate non-modified diruthenium complexes, showing that this type of conjugates are a promising approach for obtaining new antiparasitic compounds with reduced toxicity.
Topics: Humans; Antiparasitic Agents; Ruthenium; Toxoplasma; Galactose
PubMed: 36677958
DOI: 10.3390/molecules28020902 -
The Journal of Biological Chemistry Sep 1980D-Tagatose-6-phosphate kinase, an inducible enzyme that functions in the metabolism of lactose and D-galactose in Staphylococcus aureus, was purified about 300-fold from...
D-Tagatose-6-phosphate kinase, an inducible enzyme that functions in the metabolism of lactose and D-galactose in Staphylococcus aureus, was purified about 300-fold from an extract of D-galactose-grown cells. The enzyme catalyzed the nucleoside triphosphate-dependent phosphorylation of both D-tagatose 6-phosphate and D-fructose 6-phosphate. Although the Vmax values were equal for these two substrates, the apparent Km values differed by 10,000-fold, being 16 micro M for D-tagatose 6-phosphate and 150 mM for D-fructose 6-phosphate. The purified enzyme was free from the constitutive D-fructose-6-phosphate kinase. Phosphoryl donors used by D-tagatose-6-phosphate kinse, listed in order of decreasing rates at saturating concentrations were GTP, UTP ITP ATP, CTP, and TTP; the Km values were 0.38, 0.91, 0.17, 0.16, 18, and 20 mM, respectively. The enzyme appeared to be nonallosteric; it exhibited Michaelis-Menten kinetics and was not inhibited by high concentrations of MgATP. However, it was activated 3- to 4-fold by 33.3 mM K+, NH4+, Rb+, and Cs+, and was inhibited 31 to 65% by 33.3 mM Na+ and Li+. It was inactivated reversibly by the thiol reagent, N-ethylmaleimide. The subunit molecular weight was estimated to be 52,000, and the native enzyme appeared to be a dimer with a sedimentation coefficient of 6.8 S. Data on stability, pH optimum, and inducibility of the enzyme are also presented.
Topics: Cations, Monovalent; Enzyme Induction; Galactose; Hexosephosphates; Hydrogen-Ion Concentration; Kinetics; Lactose; Molecular Weight; Phosphotransferases; Phosphotransferases (Alcohol Group Acceptor); Staphylococcus aureus; Substrate Specificity
PubMed: 6251066
DOI: No ID Found -
Bioconjugate Chemistry Feb 2018The use of glycosylated compounds is actively pursued as a therapeutic strategy for cancer due to the overexpression of various types of sugar receptors and transporters...
The use of glycosylated compounds is actively pursued as a therapeutic strategy for cancer due to the overexpression of various types of sugar receptors and transporters on most cancer cells. Conjugation of saccharides to photosensitizers such as porphyrins provides a promising strategy to improve the selectivity and cell uptake of the photosensitizers, enhancing the overall photosensitizing efficacy. Most porphyrin-carbohydrate conjugates are linked via the carbon-1 position of the carbohydrate because this is the most synthetically accessible approach. Previous studies suggest that carbon-1 galactose derivatives show diminished binding since the hydroxyl group in the carbon-1 position of the sugar is a hydrogen bond acceptor in the galectin-1 sugar binding site. We therefore synthesized two isomeric porphyrin-galactose conjugates using click chemistry: one linked via the carbon-1 of the galactose and one linked via carbon-3. Free base and zinc analogs of both conjugates were synthesized. We assessed the uptake and photodynamic therapeutic (PDT) activity of the two conjugates in both monolayer and spheroidal cell cultures of four different cell lines. For both the monolayer and spheroid models, we observe that the uptake of both conjugates is proportional to the protein levels of galectin-1 and the uptake is suppressed after preincubation with an excess of thiogalactose, as measured by fluorescence spectroscopy. Compared to that of the carbon-1 conjugate, the uptake of the carbon-3 conjugate was greater in cell lines containing high expression levels of galectin-1. After photodynamic activation, MTT and lactate dehydrogenase assays demonstrated that the conjugates induce phototoxicity in both monolayers and spheroids of cancer cells.
Topics: Carbon; Cell Line, Tumor; Galactose; Humans; Neoplasms; Photochemotherapy; Photosensitizing Agents; Porphyrins
PubMed: 29313666
DOI: 10.1021/acs.bioconjchem.7b00636 -
Marine Drugs Apr 20222-keto-3-deoxy sugar acids, which have potential as precursors in medicinal compound production, have gained attention in various fields. Among these acids,...
2-keto-3-deoxy sugar acids, which have potential as precursors in medicinal compound production, have gained attention in various fields. Among these acids, 2-keto-3-deoxy-l-galactonate (KDGal) has been biologically produced from D-galacturonate originating from plant-derived pectin. KDGal is also found in the catabolic pathway of 3,6-anhydro-l-galactose (AHG), the main component of red-algae-derived agarose. AHG is converted to 3,6-anhydrogalactonate by AHG dehydrogenase and subsequently isomerized to KDGal by 3,6-anhydrogalactonate cycloisomerase. Therefore, we used the above-described pathway to produce KDGal from agarose. Agarose was depolymerized to AHG and to agarotriose (AgaDP3) and agaropentaose (AgaDP5), both of which have significantly higher molecular weights than AHG. When only AHG was converted to KDGal, AgaDP3 and AgaDP5 remained unreacted. Finally, KDGal was effectively purified from the enzymatic products by size-exclusion chromatography based on the differences in molecular weights. These results show that KDGal can be enzymatically produced and purified from agarose for use as a precursor to high-value products.
Topics: Galactose; Pectins; Rhodophyta; Seaweed; Sepharose
PubMed: 35621939
DOI: 10.3390/md20050288 -
American Journal of Physiology.... Jul 2008Metabolism of galactose is a specialized liver function. The purpose of this PET study was to use the galactose analog 2-[(18)F]fluoro-2-deoxygalactose (FDGal) to...
Metabolism of galactose is a specialized liver function. The purpose of this PET study was to use the galactose analog 2-[(18)F]fluoro-2-deoxygalactose (FDGal) to investigate hepatic uptake and metabolism of galactose in vivo. FDGal kinetics was studied in 10 anesthetized pigs at blood concentrations of nonradioactive galactose yielding approximately first-order kinetics (tracer only; n = 4), intermediate kinetics (0.5-0.6 mmol galactose/l blood; n = 2), and near-saturation kinetics (>3 mmol galactose/l blood; n = 4). All animals underwent liver C15O PET (blood volume) and FDGal PET (galactose kinetics) with arterial and portal venous blood sampling. Flow rates in the hepatic artery and the portal vein were measured by ultrasound transit-time flowmeters. The hepatic uptake and net metabolic clearance of FDGal were quantified by nonlinear and linear regression analyses. The initial extraction fraction of FDGal from blood-to-hepatocyte was unity in all pigs. Hepatic net metabolic clearance of FDGal, K(FDGal), was 332-481 ml blood.min(-1).l(-1) tissue in experiments with approximately first-order kinetics and 15.2-21.8 ml blood.min(-1).l(-1) tissue in experiments with near-saturation kinetics. Maximal hepatic removal rates of galactose were on average 600 micromol.min(-1).l(-1) tissue (range 412-702), which was in agreement with other studies. There was no significant difference between K(FDGal) calculated with use of the dual tracer input (Kdual(FDGal)) or the single arterial input (Karterial(FDGal)). In conclusion, hepatic galactose kinetics can be quantified with the galactose analog FDGal. At near-saturated kinetics, the maximal hepatic removal rate of galactose can be calculated from the net metabolic clearance of FDGal and the blood concentration of galactose.
Topics: Animals; Chromatography, High Pressure Liquid; Female; Fluorine Radioisotopes; Fucose; Galactose; Hepatocytes; Liver; Logistic Models; Nonlinear Dynamics; Positron-Emission Tomography; Swine
PubMed: 18483186
DOI: 10.1152/ajpgi.00004.2008 -
Journal of Nuclear Medicine : Official... Oct 2011Accurate quantification of regional liver function is needed, and PET of specific hepatic metabolic pathways offers a unique method for this purpose. Here, we quantify...
UNLABELLED
Accurate quantification of regional liver function is needed, and PET of specific hepatic metabolic pathways offers a unique method for this purpose. Here, we quantify hepatic galactose elimination in humans using PET and the galactose analog 2-(18)F-fluoro-2-deoxy-d-galactose ((18)F-FDGal) as the PET tracer.
METHODS
Eight healthy human subjects underwent (18)F-FDGal PET/CT of the liver with and without a simultaneous infusion of galactose. Hepatic systemic clearance of (18)F-FDGal was determined from linear representation of the PET data. Hepatic galactose removal kinetics were determined using measurements of hepatic blood flow and arterial and liver vein galactose concentrations at increasing galactose infusions. The hepatic removal kinetics of (18)F-FDGal and galactose and the lumped constant (LC) were determined.
RESULTS
The mean hepatic systemic clearance of (18)F-FDGal was significantly higher in the absence than in the presence of galactose (0.274 ± 0.001 vs. 0.019 ± 0.001 L blood/min/L liver tissue; P < 0.01), showing competitive substrate inhibition of galactokinase. The LC was 0.13 ± 0.01, and the (18)F-FDGal PET with galactose infusion provided an accurate measure of the local maximum removal rate of galactose (V(max)) in liver tissue compared with the V(max) estimated from arterio-liver venous (A-V) differences (1.41 ± 0.24 vs. 1.76 ± 0.08 mmol/min/L liver tissue; P = 0.60). The first-order hepatic systemic clearance of (18)F-FDGal was enzyme-determined and can thus be used as an indirect estimate of galactokinase capacity without the need for galactose infusion or knowledge of the LC.
CONCLUSION
(18)F-FDGal PET/CT provides an accurate in vivo measurement of human galactose metabolism, which enables the quantification of regional hepatic metabolic function.
Topics: Aged; Female; Fluorine Radioisotopes; Fucose; Galactose; Humans; Infusions, Intravenous; Kinetics; Liver; Liver Circulation; Male; Middle Aged; Positron-Emission Tomography; Radiopharmaceuticals; Reference Values; Tomography, X-Ray Computed
PubMed: 21875925
DOI: 10.2967/jnumed.111.092924 -
Analytical Sciences : the International... 2011To generate a new specific recognition module for the enrichment and detection of ricin, galactose-functionalized silanized magnetic iron-oxide nanoparticles...
To generate a new specific recognition module for the enrichment and detection of ricin, galactose-functionalized silanized magnetic iron-oxide nanoparticles (Gal-SiMNPs) were assembled by amino-silanized MNPs (amino-SiMNPs) and a galactose linker. Amino-SiMNPs were produced by a coprecipitation method, and were coated with double layers of silica and aminosilane by hydrolysis of tetraethoxysilane and 3-aminopropyltriethoxysilane, respectively. A galactose with an amido-acid linker was synthesized by four steps of chemical modification from O-acetyl protected galactose. The diameters of Gal-SiMNPs were characterized as being 60 ± 20 nm. The average amount of galactose-loading and ricin-binding on Gal-SiMNPs was 30 ± 2 µg galactose and 29 ± 2 µg ricin toxin on the surface of 1 mg of Gal-SiMNPs, respectively. Furthermore, a rapid, simple and efficient colorimetric assay was established for the detection of ricin based on the Gal-SiMNPs, and the limits of detection (LODs) of 2 and 4 ng/mL for ricin in physiological buffer and serum were obtained, respectively.
Topics: Ferric Compounds; Galactose; Magnetics; Nanoparticles; Particle Size; Ricin; Surface Properties
PubMed: 21233555
DOI: 10.2116/analsci.27.19