Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GALACTOSE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
PubMed2004

Cytochemical study of role of alpha-d-mannose- and beta-d-galactose-containing glycoproteins in apoptosis.

Recently, we found increased levels of alpha-d-mannose- and beta-d-galactose-containing glycoproteins in plasma membrane of the apoptotic murine leukemia L1210 cells (Bilyy & Stoika 2003). That indicator was suggested to be a novel marker of apoptosis in L1210 cells. The aim of our present work was to reveal if these changes in glycoprotein expression can be common for apoptotic cells of different origin and for various ways of apoptosis induction. It was demonstrated that an elevated expression of plasma membrane glycoproteins rich in alpha-d-mannose and beta-d-galactose did not depend on type of cell line and its tissue origin as well as on nature of apoptosis-inducing agent. We also found that an increase in membrane glycoprotein expression was dependent on concentration of apoptosis-inducing agent and was time-dependent. Changes in glycoproteins' expression were detected as early as 9-12 hours after apoptosis induction. Two hours pretreatment of cells with non-labeled lectin decreased plasma membrane staining with corresponding peroxidase-labeled lectin, probably because of lectin-induced internalization of specific membrane glycoproteins. PSL-lectin-affinity procedure was developed for isolation of apoptotic cells from their mixed population with normal cells. Lectin-dependent agglutination analysis showed that this process occurs at much lower lectin dilutions in the apoptotic cells than in the non-apoptotic cells. Thus, we found that alpha-d-mannose- and beta-d-galactose-containing glycoproteins can be used for lectinocytochemical detection, study and isolation of apoptotic cells.

Animals↗
PubMed1988

Separation of oligosaccharides containing terminal alpha-linked galactose residues by affinity chromatography on Griffonia simplicifolia I bound to concanavalin A-sepharose.

The seeds of Griffonia simplicifolia contain a family of five isolectins (GS-I) (L. A. Murphy and I. J. Goldstein (1977) J. Biol. Chem. 252, 4739-4742) that bind with high affinity to glycoconjugates containing terminal nonreducing alpha-linked galactose residues. Here, we report that GS-I itself is bound via its high mannose-type, Asn-linked sugar chains to immobilized concanavalin A (Con A-Sepharose). The GS-I in the GS-I-Con A-Sepharose complex retains its ability to bind glycoconjugates containing terminal alpha-linked galactose residues. This convenient method to immobilize GS-I is rapid and quantitative. We have exploited this affinity system to separate oligosaccharides based on their number of terminal alpha-linked D-galactose residues.

Animals↗
PubMed1988

Biocytin hydrazide--a selective label for sialic acids, galactose, and other sugars in glycoconjugates using avidin-biotin technology.

Biocytin hydrazide (BCHZ), a new, water-soluble, long-chained, biotin-containing hydrazide, was synthesized and used for the selective nonradioactive detection of glycoconjugates. Procedures were developed for labeling glycoconjugates on blots. The method involves either chemical (periodate-induced) or enzymatic (via galactose oxidase) oxidation of glycoconjugates, the resultant aldehyde groups are then labeled with biocytin hydrazide, followed by interaction with an avidin-based enzyme probe. Since the biotin-containing reagent is a relatively small, charged molecule, the primary labeling step may be carried out on intact cells and on membrane preparations as well as on blotted samples. On blots, the labeling pattern was similar for both periodate- and galactose oxidase-induced biotinylation procedures. In contrast, periodate-induced labeling of either erythrocyte membranes or cells (prior to blotting) produced an altered labeling pattern. Combined enzyme-induced biotinylation of membranes or cells resulted in a pattern similar to that observed for the direct staining of blots. Using galactose oxidase on human erythrocyte membranes, the procedure was sensitive enough to selectively label the Band 3 lactosaminoglycoprotein.

Avidin↗
PubMed1990

Synthesis, purification, and characterization of 2,4,6-trinitrophenyl-UDP-galactose: a fluorescent substrate for galactosyltransferase.

Glycosyltransferases enzymatically transfer monosaccharides from sugar-nucleotides to complex oligosaccharide chains and, as cell surface molecules, exhibit receptor-like activity. We have modified the substate UDP-galactose to produce a compound that has useful absorbance and fluorescence properties upon binding to galactosyltransferase (GalTase). Using strategies similar to those for preparing fluorescent ATP analogs, we were able to synthesize 2,4,6-trinitrophenyl-5'-UDP-galactose (TUG). In solution, the absorbance properties of TUG are pH dependent, with absorbance maxima at 260, 408, and 453 nm and an isobestic point at 353 nm. In the presence of soluble GalTase extracted from bovine milk, TUG exhibited an excitation maximum at 368 nm with emission maxima at 436 and 533 nm; in the absence of GalTase only the 533-nm peak was present. Under enzymatic conditions, TUG acted as a competitive substrate of UDP-galactose with GalTase. Under noncatalytic conditions, the fluorescence emission of TUG at 436 nm increased monotonically with Gal-Tase concentration, with a half-maximal response at approximately 4 microM. This compound may be useful for quantifying GalTase function as both an enzyme and a cell adhesion molecule.

Binding, Competitive↗
PubMed1991

A high performance liquid chromatography method for the analysis of glycosphingolipids using galactose oxidase/NaB3H4 labeling of intact cells and synaptosomes.

The major objective of this study was to combine an HPLC method with a galactose oxidase/NaB3H4 labeling method to allow both a chemical quantitation of individual glycolipids and analysis of their 3H labeling. Neutral glycolipids in whole cells were oxidized with galactose oxidase, and the resultant aldehydes were radiolabeled by reduction with tritiated sodium borohydride. Gangliosides, oxidized with galactose oxidase, either were reduced while in the native state in the whole cell or were first extracted and then reduced. Tritiated glycolipids were perbenzoylated and separated by HPLC. Ultraviolet detection of the derivatives was at 230 nm. Incorporated radioactivity was determined either by collecting fractions from the HPLC separation and counting on a liquid scintillation spectrometer or with a flow-through counter. The order of the derivatization and reduction is critical. Reduction of glycolipids prior to derivatization yielded sharp uv and radioactive peaks. Perbenzoylation of the oxidized glycolipids prior to reduction yielded multiple uv peaks, a noisy baseline, and broad radioactive peaks which did not always have a corresponding uv peak. The labeled neutral glycolipids were stable at -40 degrees C for at least 14 days, and gangliosides were stable at -15 degrees C for at least 14 days. When samples were stored at 20 degrees C there was a time-dependent decrease in the glycolipid/internal standard uv peak area ratio for GbOse4 and GbOse3 apparent by 28 days after perbenzoylation. The distribution of radiolabel among peaks showed no change with time or temperature. We adapted the technique to allow 3H labeling of glycolipids from monolayers of cultured glioma cells and from mouse brain synaptosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Importance of hydroxyls at positions 3, 4, and 6 for binding to the "galactose" site of beta-galactosidase (Escherichia coli).

Values of kinetic inhibition constants representing dissociation constants of inhibitors interacting with the free form of beta-galactosidase ('galactose" site) were determined for a large number of monosaccharides and alcohols. The studies showed that when hydroxyl groups were present at positions 3, 4, and 6 and were in the same orientation as in galactose, binding to the 'galactose" site was good. Alterations in the position of or a lack of a hydroxyl at any of these three positions decreased binding dramatically. The overall binding specificity thus depends to a large extent on these three positions. Positions 3 and 4 were critical. A misorientation at either position eliminated most of the binding. Position 6 was a little more independent. The absence of a hydroxyl at that position did not totally eliminate the binding. The position 2 hydroxyl did not seem to be important for binding as its absence or orientation had only a small effect on the binding capacity. Studies regarding position 5 were inconclusive but since a minimum of four hydroxyl groups seemed important for binding and since positions 3, 4, and 6 are important the 5 position may also be of significance. The work also showed that p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-L-arabinofuranoside, p-nitrophenyl-beta-D-xylopyranoside, cellobiose, and gentiobiose were not substrates in spite of the fact that the nitrophenyl groups made some of these bind quite well. Thus, not only are the presence and configuration of the hydroxyls at positions 3 and 4 important for binding, they are also important in catalysis. p-Nitrophenyl-beta-D-fucopyranoside was a substrate indicating that the 6 position hydroxyl is not as important for production binding as are the hydroxyls at positions 3 and 4.

Bacterial Proteins↗
PubMed1985

Oxidation rates of some desialylated glycoproteins by galactose oxidase.

Patterns of oxidation of dilute solutions of desialylated fetuin and submaxillary mucin by galactose oxidase have been examined. A significant portion (20-40%) of the terminal galactosyls exposed on the glycoproteins, which theoretically were expected to be accessible to the enzyme, was not oxidized. In comparison, galactosyls in oligosaccharides released from completely desialylated glycoproteins were oxidized more effectively with an apparently lower degree of crypticity to the enzyme. Partial desialylation usually resulted in a reduction of both the rate and the final level of substrate oxidation. A second cycle of oxidation of a desialylated substrate earlier oxidized by galactose oxidase and then reduced by NaB3H4 revealed a selectivity in the pattern of galactosyl oxidation. The same galactosyl residues oxidized in the first cycle were again the most susceptible to oxidation in the second cycle, leaving unmodified the same fraction of galactosyls throughout both cycles. The relevance of these results to the application of the galactose oxidase-NaBH4 procedure for detecting and measuring desialylated glycoconjugates in solution and in biological membranes is discussed.

Animals↗
PubMed1975

Sugar transport by intestine. Escape of galactose from preloaded mucosa of hamster jejunum.

Everted hamster jejunum was loaded with D-galactose and then escape into an initially galactose-free mucosal solution was followed. Mucosal anaerobiosis greatly increased the rate of escape, an effect which might have been caused by inhibiting reuptake from the unstirred layer and/or by augmenting the ease of unidirectional efflux across the brush border membrane. The former effect was expected because of our previous results from influx studies, and the main object here was to find out if the ease of efflux is affected by anaerobiosis. With phlorizin present in the mucosal solution during escape, information about unidirectional efflux was obtainable. We estimated that 10(-4) M phlorizin inhibited the ease of efflux via the phlorizin-sensitive pathway by about 65%. Apparently the reason why mucosal phlorizin accelerates escape of sugar from loaded mucosa, an effect which has been reported previously by others, is that it inhibits unidirectional efflux less effectively than it inhibits reuptake from the unstirred layer. Residual efflux via the phlorizin-sensitive pathway was markedly increased by mucosal anaerobiosis. This increase did not require an elevation of intracellular Na+ concentration. These results, together with those of our previous study, show that mucosal anaerobiosis abolishes uphill transport of galactose across the brush border of hamster jejunum by inhibiting unidirectional influx and by increasing the ease of unidirectional efflux. Neither of these effects requires a rise in intracellular Na+ concentration.

Anaerobiosis↗
PubMed1978

Effects of insulin on the uptake of D-galactose by isolated rat epididymal fat cells.

In muscle, insulin stimulates uptake of D-galactose as well as D-glucose and certain other sugar isomers (Kono, T. and Colowick, S.P. (1961) Arch. Biochem. Biophys. 93, 514--519). In fat cells, the hormone also stimulates uptake of D-glucose and certain other monosaccharides. Nonetheless, the hormone does not increase the uptake, as determined by the utilization, of D-galactose by fat cells (Ball, E.G. and Cooper, O. (1960) J. Biol. Chem. 235, 584--588; Kuo, J.F. and Dill, I.K. (1969) Biochim. Biophys. Acta 177, 17--26). As pointed out by Ball and Cooper, this does not necessarily indicate that insulin has no effect on the membrane transport of D-galactose in fat cells. The possible effect of the hormone on transport may not be seen in the utilization data if the intracellular metabolism is considerably slower than the rate of transport and insensitive to insulin.

Adipose Tissue↗
PubMed1982

Galactose oxidase action on GM1 ganglioside in micellar and vesicular dispersions.

GM1 ganglioside was dispersed in different membrane-mimicking systems and the effect of dispersion on GM1 oxidation by galactose oxidase was studied. The following membrane-mimicking systems were used: homogeneous micelles of GM1; mixed micelles (at different proportions of constituents) of GM1 with either GD1a ganglioside (which is resistant to the enzyme), or the non-ionic detergent Triton X-100, or bovine serum albumin; small unilamellar vesicles of egg phosphatidylcholine (PC), containing various proportions of GM1. As a reference substrate not involved in membranous systems and freely interacting with the enzyme, the oligosaccharide portion of GM1 (DesGM1) was employed. The apparent Vmax of the enzyme was dramatically dependent on the type of GM1 dispersion. The lowest value was recorded on homogeneous micelles of GM1 and on mixed GM1-GD1a micelles. From this value, the Vmax increased 2-fold with GM1-bovine serum albumin lipoprotein micelles, up to 1400-fold with mixed GM1-Triton X-100 (optimal molar ratio, 1:13.8) micelles, and up to 14000-fold on PC vesicles containing 8 mol% GM1 (this proportion was optimal for enzyme activity on vesicles). The activity developed on these latter vesicles turned out to be still greater (2-fold) than that displayed on DesGM1. The apparent Km had very similar values in all different membrane systems; in contrast, it was markedly greater on DesGM1. Both Triton X-100 micelles and PC vesicles did not appreciably alter the kinetics of galactose oxidase action on pure galactose, indicating that the above effects are dependent on the intrinsic characteristics of the membrane-like systems containing gangliosides.

Animals↗
PubMed1983

Reconstitution of the GalP galactose transport activity of Escherichia coli into liposomes made from soybean phospholipids.

Galactose transport activity from Escherichia coli was solubilized with octyl glucoside, and reconstituted into liposomes made from soybean or E. coli lipid. Galactose counterflow in the proteoliposomes was inhibited by glucose, talose, 2-deoxygalactose and 6-deoxygalactose, confirming that it was due to GalP and not one of the other E. coli galactose transport systems.

Biological Transport, Active↗
PubMed1989

Composition and toxicity of lipids from Rhodococcus rhodochrous grown on medium containing galactose, glucose or mannose.

Rhodococcus rhodochrous, a producer of mycolic acid of approx. C40, exhibited a higher cellular mass yield when grown on glucose than when grown on galactose or mannose. The cellular content of the diethyl ether-soluble lipids in microorganisms cultivated on glucose or mannose varied with the incubation time, while that of microorganisms grown on galactose remained constant. The lipids extracts from cells cultivated on different hexoses and collected at the exponential phase of growth were more toxigenic; this property was related in general to the content of glycolipid. On the other hand, cells cultivated on galactose or mannose had a higher quantity of glycolipid in the exponential phase, while the glycolipid content of those grown on glucose remained approximately constant. Amongst the components of the lipid extract, the glycolipid fraction was the sole fraction bearing toxic property. Neutral plus fatty acids and phospholipids displayed no similar characteristic.

Animals↗
PubMed1975

Subunit structure of D-galactose dehydrogenase from Pseudomonas saccharophila.

1. D-Galactose dehydrogenase from Pseudomonas saccharophila (molecular weight 102 000) dissociates in 8 M urea into its subunits (molecular weight 25 000) which migrate in polyacrylamide gels, containing 8 M urea, as a single band. 2. The N-terminal residue determination by the dansyl method revealed only serine. 3. The C-terminal group determination with carboxypeptidase A and B indicated the sequence -Tyr-His-Leu. Leucine as the single C-terminal amino acid was confirmed by the tritiation method and by tritiation and subsequent degradation with carboxypeptidases. 4. The fragmentation of D-galactose dehydrogenase (24 mol methionine per mol enzyme) by CNBr resulted in six peptides, as detected in disc electrophoresis and substantiated by end group determination, indicating the identity of the subunits. 5. The treatment of D-galactose dehydrogenase (24 mol lysine and 52 mol arginine per mol enzyme) with trypsin and subsequent peptide mapping showed 21, perhaps 22 peptides, indicating a structure comprising four identical subunits.

Alcohol Oxidoreductases↗
PubMed1980

Studies on factor VIII-related protein. IV. Interaction of galactose-specific lectins with human factor VIII/Von Willebrand factor.

Factor VIII of human cryoprecipitate was purified and fractionated on Sepharose CL-2B into three fractions of progressively decreasing multimer size and ristocetin cofactor activity. Following complete disulfide reduction, the resulting subunits were electrophoresed on 3% polyacrylamide gels and subsequently stained with two galactose-specific, fluorescein-labelled lectins from Ricinus communis (RCAI and RCAII). Measurements of fluorescence indicated that the reduced chains, derived from the largest factor VIII multimers, have stronger binding affinity for both lectins than those obtained after reduction of smaller factor VIII species. Ristocetin cofactor activity of purified factor VIII was competitively inhibited by both Ricinus lectins and by concanavalin A. RCAI-lectin was found to be a considerably more efficient inhibitor than RCAII or concanavalin A. Following removal of sialic acid from factor VIII, the inhibiting effect of RCAII-lectin was markedly potentiated, probably by exposing additional galactose residues, some of which must be located close to the ristocetin cofactor 'active site' of factor VIII. Ristocetin cofactor activity was also strongly inhibited with RCAII-lectin for binding sites which are located on the surface factor VIII multimers. Our results suggest that RCAI-lectin, which contains galactose-specific binding sites per molecule, and anti-factor VIII antibodies inhibit ristocetin cofactor activity by crosslinking and aggregation of factor VIII multimers.

Antibodies↗
PubMed1984

Factors regulating the specific activity of galactose-1-phosphate uridyltransferase during perfusion of suckling rat liver.

The regulation of the specific activity of galactose-1-phosphate uridyltransferase (E.C.2.7.7.12) has been studied using the hexose-perfused suckling rat liver as a model. Perfusion in the recirculating mode with galactose concentrations up to 4mM resulted in enzyme activity which fluctuated significantly during a 90-min experimental period. A concentration of 10 mM galactose stabilized the enzyme activity at levels found in unperfused liver. The same stabilizing effect was seen with 10 mM glucose. The elevated transferase specific activity observed after 30 min recirculating perfusion was not seen when the nonrecirculation mode was employed suggesting a factor in the recirculating medium may mediate this effect.

Animal Population Groups↗
PubMed1981

Galactose oxidase labeling of membrane proteins from human brain white matter.

The use of galactose oxidase (EC 1.1.3.9) and tritiated sodium borohydride for labeling of membrane glycoproteins, described by Gahmberg and Hakomori, has previously been applied to the study of myelin glycoproteins of experimental animals. Rat brain myelin glycoproteins have been studied by sequential lectin affinity of chromatography and recently the lectin-binding capacity of rat central nervous system myelin glycoproteins has been characterized. Complex heterogeneity of the glycoprotein pattern of rat central nervous system myelin has been reported, and so a variety of glycoproteins can be expected to exist in human white matter membranes. Application of the galactose oxidase procedure to the study of human brain membranes could be useful in research concerning certain neurological diseases if the properties of autopsy brain material are taken into account. In this study, membrane proteins of human autopsy brain white matter were subjected to the galactose oxidase/NaB3H4 labeling procedure and the membrane labeled by this method or by the [3H]acetic anhydride techniques were studied by lectin affinity chromatography using Lens culinaris phytohemagglutinin (lentil lectin) attached to Sepharose 4B beads.

Cerebral Cortex↗
PubMed1990

Synthesis of L-gulose, L-galactose, and their acetylated aldehydo forms from 6-S-phenyl-6-thio-D-hexoses.

Methyl 6-S-phenyl-6-thio-a-D-glucopyranoside, prepared in high yield from methyl a-D-glucopyranoside by the action of diphenyl disulfide and tributylphosphine in pyridine, was converted into 6-S-phenyl-6-thio-D-glucitol pentaacetate (7) by sequential hydrolysis, borohydride reduction, and acetylation. Oxidation of 7 with 3-chloroperoxybenzoic acid gave the corresponding S-epimeric sulfoxides, which underwent Pummerer rearrangement to 1-epimeric L-gulose S-phenyl monothiohemiacetal hexaacetates. Boron trifluoride-catalyzed reaction of the latter with thiophenol gave the analogous diphenyl dithioacetal, whereas base-catalyzed methanolysis led to free L-gulose. Treatment of 7 with N-chlorosuccinimide afforded 1-epimeric 1-chloro-1-S-phenyl-1-thio-L-gulitol pentaacetates, which were hydrolyzed to provide aldehydo-L-gulose pentaacetate. The same reaction sequences were performed with 6-S-phenyl-6-thio-D-galactose, synthesized in two steps from 1,2:3,4-di-O-isopropylidene-a-D-galactopyranose, furnishing ultimately L-galactose, its diphenyl dithioacetal pentaacetate, and aldehydo-L-galactose pentaacetate. Similar reaction sequences for the chain-terminal interchange of oxidation state in other omega-S-phenyl-omega-thioaldoses may prove useful for the preparation of less-common sugar derivatives.

Acetylation↗
PubMed1994

Binding of D-galactose-terminated ligands to rabbit asialoglycoprotein receptor.

The binding affinities of a series of D-galactose-terminated glycerol glycosides and oligosaccharides for the asialoglycoprotein receptor isolated from rabbit liver were determined in vitro using a radioreceptor-inhibition assay with 125I-asialoorosomucoid. The relative affinities of the synthetic ligands increased with the number of exposed D-galactose termini. Of the compounds examined, 1,2,3-tri-O-beta-lactosylglycerol associated with the greatest affinity (estimated Kd = 7.97 x 10(-5) M). Examination of the affinities of the synthetic series indicated that both the number and propinquity of the D-galactose termini influenced the strength of the binding interactions.

Animals↗