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Showing papers on "Melibiose published in 2001"


Journal ArticleDOI
TL;DR: These peptide opiates bearing the pharmacophore H-Tyr-c[DCys-Gly-Phe-DCys]- were designed to probe the significance of the glycoside moiety and the carbohydrate-peptide linkage region in blood-brain barrier (BBB) transport, opiate receptor binding, and analgesia.
Abstract: The synthesis of 18 N-alpha-FMOC-amino acid glycosides for solid-phase glycopeptide assembly is reported. The glycosides were synthesized either from the corresponding O'Donnell Schiff bases or from N-alpha-FMOC-amino protected serine or threonine and the appropriate glycosyl bromide using Hanessian's modification of the Koenigs-Knorr reaction. Reaction rates of D-glycosyl bromides (e.g., acetobromoglucose) with the L- and D-forms of serine and threonine are distinctly different and can be rationalized in terms of the steric interactions within the two types of diastereomeric transition states for the D/L and D/D reactant pairs. The N-alpha-FMOC-protected glycosides [monosaccharides Xyl, Glc, Gal, Man, GlcNAc, and GalNAc; disaccharides Gal-beta(1-4)-Glc (lactose), Glc-beta(1-4)-Glc (cellobiose), and Gal-alpha(1-6)-Glc (melibiose)] were incorporated into 22 enkephalin glycopeptide analogues. These peptide opiates bearing the pharmacophore H-Tyr-c[DCys-Gly-Phe-DCys]- were designed to probe the significance of the glycoside moiety and the carbohydrate-peptide linkage region in blood-brain barrier (BBB) transport, opiate receptor binding, and analgesia.

129 citations


Journal ArticleDOI
TL;DR: Kinetic experiments showed that α-Gal I hydrolyzed p-nitrophenyl-α-Image-galactopyranoside and melibiose more efficiently than α-gal II-IV, which further signifies the difference between α- Galactosidases of family 27 and 36.

95 citations


Journal ArticleDOI
TL;DR: Raffinose oligosaccharides are the major factors responsible for flatulence following ingestion of soybean derived products and removal from seeds or soymilk would then have a positive impact on the acceptance of soy-based foods.

95 citations


Journal ArticleDOI
TL;DR: It is demonstrated here that micronemal protein 1 (MIC1) is a lactose-binding lectin, which suggests that MIC1 may act through its lectin activity during T. gondii infection.
Abstract: Host cell invasion by Toxoplasma gondii is a multistep process with one of the first steps being the apical release of micronemal proteins that interact with host receptors. We demonstrate here that micronemal protein 1 (MIC1) is a lactose-binding lectin. MIC1 and MIC4 were recovered in the lactose-eluted (Lac(+)) fraction on affinity chromatography on immobilized lactose of the soluble antigen fraction from tachyzoites of the virulent RH strain. MIC1 and MIC4 were both identified by N-terminal microsequencing. MIC4 was also identified by sequencing cDNA clones isolated from an expression library following screening with mouse polyclonal anti-60/70 kDa (Lac(+) proteins) serum. This antiserum localized the Lac(+) proteins on the apical region of T. gondii tachyzoites by confocal microscopy. The Lac(+) fraction induced hemagglutination (mainly type A human erythrocytes), which was inhibited by beta-galactosides (3 mM lactose and 12 mM galactose) but not by up to 100 mM melibiose (alpha-galactoside), fucose, mannose, or glucose or 0.2 mg/ml heparin. The lectin activity of the Lac(+) preparation was attributed to MIC1, because blotted MIC1, but not native MIC4, bound human erythrocyte type A and fetuin. The copurification of MIC1 and MIC4 may have been due to their association, as reported by others. These data suggest that MIC1 may act through its lectin activity during T. gondii infection.

79 citations


Journal ArticleDOI
TL;DR: Modifications of PNA-binding glycoproteins, including selective removal of O-linked oligosaccharides and treatment with glycosidases revealed that Galbeta1-->4GlcNAc (LacNAc) was ineffective while terminal alpha-linked galactose (TAG) was excellent as sugar moiety in glycoproteinins for their recognition by PNA.

45 citations


Journal ArticleDOI
TL;DR: In this paper, nutritional requirements of Lactobacillus fermentum Ogi El were studied in order to define a simplified fermentation medium, which allowed, under anaerobiosis, similar results to be obtained as in MRS medium, but without biphasic fermentation kinetics.
Abstract: Aims: Nutritional requirements of Lactobacillus fermentum Ogi El were studied in order to define a simplified fermentation medium. Methods and Results: When grown with MRS-medium in 21 bioreactors, a biphasic pattern of growth and metabolite production was observed. Study of nutritional requirements resulted in a simplified medium (SYAM) that allowed, under anaerobiosis, similar results to be obtained as in MRS medium, but without biphasic fermentation kinetics. The best substrates for both growth and amylase production were starch and maltose. Although melibiose, raffinose, fructose, sucrose and glucose also supported growth, lower amylase activity was observed. Conclusions: The physiology of the strain can be investigated with SYAM medium, using either starch or maltose as substrate. The strain also presented potential for a-galactoside fermentation. Significance and Impact of the Study: Lactobacillus fermentum was one of the dominant bacteria of African maize dough fermentations. Amylolytic strains with activity against other compounds (i.e. raffinose) suggested a potential to be used as starter for cereal fermentation. (Resume d'auteur)

37 citations


Journal ArticleDOI
07 Mar 2001-Gene
TL;DR: The recombinant Hansenula polymorpha maltase produced in Escherichia coli hydrolyzed p-nitrophenyl-alpha-D-glucopyranoside (PNPG), sucrose, maltose and alpha-methylglucoside and did not act on melibiose, cellobiose, trehalose and o-nitro-beta- D-galactopyrside (ONPG).

35 citations


Journal ArticleDOI
TL;DR: In this paper, the authors characterized leuconostoc strains according to their antibiotic susceptibilities, carbohydrate fermentation profiles, sucrase activity patterns and plasmid content, and found that all the strains tested were resistant to the antibiotics sulphathiazole, trimethoprim and vancomycin and could be separated into two groups based on whether or not they could ferment melibiose and raffinose.
Abstract: Leuconostoc strains were characterized according to their antibiotic susceptibilities, carbohydrate fermentation profiles, sucrase activity patterns and plasmid content. All the strains tested were resistant to the antibiotics sulphathiazole, trimethoprim and vancomycin, and could be separated into two groups based on whether or not they could ferment melibiose and raffinose. Six Leuconostoc strains possessed plasmids and many produced unique sucrase activity patterns in polyacrylamide gels. These data will aid in distinguishing among physiologically similar dextran-producing leuconostocs, frequently used in research and industry.

35 citations


Journal ArticleDOI
TL;DR: It is suggested that the fast transient response reflects charge transfer within MelB during cosubstrate binding while the slow component is associated with charge transfer across the proteoliposome membrane.
Abstract: Electrogenic activity associated with the activity of the melibiose permease (MelB) of Escherichia coli was investigated by using proteoliposomes containing purified MelB adsorbed onto a solid-supported membrane. Transient currents were selectively recorded by applying concentration jumps of Na+ ions (or Li+) and/or of different sugar substrates of MelB (melibiose, thio-methyl galactoside, raffinose) using a fast-flow solution exchange system. Characteristically, the transient current response was fast, including a single decay exponential component (τ ≈ 15 ms) on applying a Na+ (or Li+) concentration jump in the absence of sugar. On imposing a Na+ (or Li+) jump on proteoliposomes preincubated with the sugar, a sugar jump in a preparation preincubated with the cation, or a simultaneous jump of the cation and sugar substrates, the electrical transients were biphasic and comprised both the fast and an additional slow (τ ≈ 350 ms) decay components. Finally, selective inactivation of the cosubstrate transloca...

34 citations


Journal ArticleDOI
TL;DR: The α-Galactosidase activity in grape flesh (Vitis venifera L. Muscat of Alexandria) was characterized by a marked increase in its activity 4 weeks after fruit bearing as discussed by the authors.

28 citations


Journal ArticleDOI
TL;DR: The enzyme showed potential to splitting off α-1,3-bound terminal galactose residues from antigens of the human blood group B(III) erythrocytes and exerted the highest affinity with respect to the synthetic substrate p-NPhGal and maximal rate of hydrolysis, compared with natural substrates.

Journal ArticleDOI
TL;DR: The egg production was observed to be unaffected by glucose and maltose although it showed significant increase with trehalose and significant decrease with melezitose, while fructose and sorbitol caused a significant decrease in the survival of the insect.
Abstract: In this study the effects of 23 carbohydrates belonging to various groups upon the survival egg production and egg of female adult Pimpla turionellae L. were investigated. The best results among the carbohydrates tested was obtained with sucrose which was also employed as control. Glucose, maltose, trehalose and melezitose on the other hand showed no significant effect. The egg production was observed to be unaffected by glucose and maltose although it showed significant increase with trehalose and significant decrease with melezitose. Fructose and sorbitol caused a significant decrease in the survival of the insect. Fructose and sorbitol did not have any significant effect upon egg production whereas galactose caused a significant decrease. With the exception of galactose, no carbohydrate caused any significant effect upon egg hatching. Although they did not produce any eggs the female insects survived for 13.17, 15.13, 11.58 and 15.83 days in mannose, melibiose, raffinose and mannitol, respectively. The shortest life span was observed in arabinose followed by α-methyl-D-glucoside, dulcitol, rhamnose, cellobiose, xylose, starch, lactose, sarbose, ribose and glycogen.

Journal ArticleDOI
TL;DR: It is suggested that Asp-59 and Lys-377 interact via a salt bridge that brings helix II and helix XI close to one another in the three-dimensional structure of the carrier.

Journal ArticleDOI
TL;DR: In this paper, the authors describe experiments in which the cysteine substitution for a charged residue was chemically changed by sulfhydryl reagents (MTSEA and MTSET) or by iodoacetic acid or through oxidation by hydrogen peroxide so as to regain the original negative charge.

Journal ArticleDOI
TL;DR: The midgut distribution of alpha-galactosidase activity supports the proposal that alpha-GalactOSidase digestion occurs at the surface of anterior midGut cells in Spodoptera frugiperda larvae.
Abstract: There are three midgut α-galactosidases (TG1, TG2, TG3) from Tenebrio molitor larvae that are partially resolved by ion-exchange chromatography. The enzymes have approximately the same pH optimum (5.0), pl value (4.6) and Mr value (46 000–49 000) as determined by gel filtration or native electrophoresis run in polyacrylamide gels with different concentrations. Substrate specificities and functions were proposed for the major T. molitor midgut α-galactosidases (TG2 and TG3) based on chromatographic, carbodiimide inactivation, Tris inhibition, and on substrate competition data. Thus, TG2 would hydrolyse α-1,6-galactosaccharides, exemplified by raffinose, whereas TG3 would act on melibiose and apparently also on digalactosyldiglyceride, the most important compound in the thylacoid membranes of chloroplasts. Most galactoside digestion should occur in the lumen of the first two thirds of T. molitor larval midguts, since α-galactosidase activity predominates there. Spodoptera frugiperda larvae have three midgut α-galactosidases (SG1, SG2, SG3) partially resolved by ion-exchange chromatography. The enzymes have similar pH optimum (5.8), pl value (7.2) and Mr value (46 000–52 000), and at least the major α-galactosidase must have an active carboxyl group in the active site. Based on data similar to those described for T. molitor, SG1 and SG3 should hydrolyse melibiose and SG3 should digest raffinose and, perhaps, also digalactosyldiglyceride. The midgut distribution of α-galactosidase activity supports the proposal that α-galactosidase digestion occurs at the surface of anterior midgut cells in Spodoptera frugiperda larvae.

Journal ArticleDOI
01 Dec 2001-Mycoses
TL;DR: To characterize strains of Microsporum canis that infect dogs and cats in Sa˜o Paulo city, 30 isolates of this dermatophyte were tested for their ability to assimilate carbon and nitrogen sources, for proteinase and phospholipase secretion, and for susceptibility to yeast killer toxins.
Abstract: To characterize strains of Microsporum canis that infect dogs and cats in Sao Paulo city, 30 isolates of this dermatophyte were tested for their ability to assimilate carbon and nitrogen sources, for proteinase and phospholipase secretion, for susceptibility to yeast killer toxins, and for susceptibility to the antifungals fluconazole, ketoconazole, itraconazole, 5-fluorocytosine and amphotericin B, in E test. All samples assimilated the nitrogen sources asparagine, ammonium sulphate, urea and sodium nitrate, as well as the carbon sources inulin, mannitol, trehalose, meso-erythritol, maltose, mannose, sorbitol, cellobiose, fructose and dextrin. Not all the samples assimilated adonitol, galactose, arabinose, rhamnose, raffinose, melibiose, ribose and sucrose, and none of them was capable of growing with dulcitol, lactose, or xylose as the only carbon source. Proteinase and phospholipase secretion was observed for most isolates. In the test of yeast killer toxin, 10 types could be identified, with four types exclusively observed in isolates from dogs and two types exclusively observed in isolates from cats. In the E test, all isolates were found to be resistant to the fluconazole and 5-fluorocytosine, while they were variably sensitive to amphotericin B, ketoconazole and itraconazole. When the data were submitted to the qualitative analysis in the matrix distance program FITOPAC, the similarity of the isolates could be assessed.

Journal ArticleDOI
TL;DR: A Thermus thermophilus selector strain for production of thermostable and thermoactive α-galactosidase was constructed by applying integration mutagenesis in combination with phenotypic selection and growth on minimal agar medium containing melibiose was achieved.
Abstract: α-Galactosidases catalyze the hydrolysis of α-1,6-linked α-galactose residues from oligosaccharides and polymeric galactomannans (9, 25, 26, 42). They have considerable potential in various industrial applications, e.g., in the sugar industry for the elimination of d-raffinose from sugar beet syrup. Due to the elevated temperatures used during the sugar manufacturing process, as well as in other industrial applications, stability and activity at high temperatures are important properties of α-galactosidases. We have been studying α-galactosidases from various bacteria with regard to their application as oligosaccharide-hydrolyzing enzymes (9, 11, 14). Our intention was to subject α-galactosidase to thermoadaptation by introducing genes encoding enzymes inactive at high temperatures into a thermophilic bacterium for subsequent selection of enzyme variants active at high temperatures. We chose Thermus thermophilus as a host due to its high transformation ability (17) and ability to use melibiose (α-galactoside) as a sole carbohydrate source (10). Thermus species have been used for expression of heterologous genes and selection of thermostable enzyme variants (16, 19, 34, 36). They possess a natural transformation system (17) and are competent regardless of their growth phase (12). Genetic systems based on the application of autonomously replicating plasmids, as well as integration vectors or vectors containing cassettes, for chromosomal integration have been established (13, 18, 22, 23, 35, 40). So far, the only antibiotic selection markers described for Thermus bacteria are thermostabilized variants of the kanamycin nucleotidyltransferase gene derived from a thermophilic Bacillus gene (28) or from the kan gene of Staphylococcus aureus (24). Expression of heterologous genes requires the inactivation of analogous genes in the host strain. In our previous work (10), we cloned the α-galactosidase gene (agaT) from T. thermophilus TH125 into Escherichia coli and subsequently disrupted the gene by site-specific integration of the kanamycin resistance marker into the agaT locus in the T. thermophilus chromosome. Sequence analysis of agaT along with flanking sequences revealed an open reading frame (ORF) downstream of and overlapping the agaT gene. The predicted translation product displayed similarity to galactose-1-phosphate uridylyltransferases (GalT) of E. coli (2) and Streptomyces lividans (1). The 3′ region of agaT and the 5′ region of galT were left intact in the site-specific integration due to the overlapping coding regions. However, characterization of the integration mutants revealed their inability to use melibiose as well as galactose. This indicated a polar transcriptional effect on the downstream galT gene. The polar effect was considered an obstruction for our purpose due to a potential growth inhibition effect of the accumulated galactose (or its metabolite derivatives) produced from melibiose hydrolysis in Gal− strains harboring recombinant α-galactosidases. Interference with growth by galactose has been described for Gal− mutants of, e.g., E. coli (30) and Bacillus subtilis (20). In this paper, we describe the establishment of a Thermus strain suitable for production of heterologous α-galactosidases. Thereby, two problems were circumvented which restricted the use of the previously constructed agaT deletion strains (10): the galactose-negative phenotype and their kanamycin resistance, which otherwise prevented plasmid selection with the kanamycin marker. Further, we demonstrate the practical value of the strain established in this work for the production of recombinant α-galactosidases and as a potential selection system for α-galactosidases active at high temperatures.

Journal ArticleDOI
TL;DR: The cloned melB gene is closely similar to the melB genes of other bacteria, but it is cryptic because of a frameshift mutation and the amino acid sequence of the C. freundii MelB was found to be most similar to those of Salmonella typhimurium and Escherichia coli MelB.
Abstract: Wild-type Citrobacter freundii cannot grow on melibiose as a sole source of carbon. The melibiose transporter gene melB was cloned from a C. freundii mutant M4 that could utilize melibiose as a sole carbon source. Although the cloned melB gene is closely similar to the melB genes of other bacteria, it is cryptic because of a frameshift mutation. Site-directed mutagenesis was used to construct a functional melB gene by deleting one nucleotide, resulting in the production of an active melibiose transporter. The active MelB transporter could utilize Na(+) and H(+) as coupling cations to melibiose transport. The amino acid sequence of the C. freundii MelB was found to be most similar to those of Salmonella typhimurium and Escherichia coli MelB. These facts are consistent with the phylogenetic relationship of bacteria and the cation coupling properties of the melibiose transporters.

Journal ArticleDOI
TL;DR: It is suggested that helix VI is imbedded in phospholipid and does not face the aqueous channel through which melibiose passes, and there was no inhibition ofmelibiose transport in any of the mutants.
Abstract: The melibiose carrier of Escherichia coli is a cytoplasmic membrane protein that mediates the cotransport of galactosides with H+, Na+, or Li+. In this study we used cysteine-scanning mutagenesis to try to gain information about the position of transmembrane helix VI in the three-dimensional structure of the melibiose carrier. We constructed 23 individual cysteine substitutions in helix VI and an adjacent loop of the carrier. The resulting melibiose carriers retained 22–100% of their ability to transport melibiose. We tested the effect of the hydrophilic sulfhydryl reagent p-chloromercuri-benzenesulfonic acid (PCMBS) on the cysteine-substitution mutants and we found that there was no inhibition of melibiose transport in any of the mutants. We suggest that helix VI is imbedded in phospholipid and does not face the aqueous channel through which melibiose passes.

Patent
19 Nov 2001
TL;DR: In this paper, a hepatic function improving agent or composition contains a nitrogen-containing compound acting as a methyl donor in the body (choline, betaine, methionine, S-adenosylmethionine), vitamin B12, folic acid, carnitine, etc.), and a hardly digestible oligosaccharide containing galactose (raffinose, lactulose, soybean oligosACcharide, galactooligosaccahride, melibiose, etc.).
Abstract: PROBLEM TO BE SOLVED: To provide a composition usable as pharmaceuticals, foods and drinks free from side effect owing to the use of a food material as the component and useful for the treatment and/or prevention of hepatic diseases such as acute hepatitis, hepatic insufficiency, chronic hepatitis, jecur adiposum and hepatocirrhosis. SOLUTION: The hepatic function improving agent or composition contains a nitrogen-containing compound acting as a methyl donor in the body (choline, betaine, methionine, S-adenosylmethionine, vitamin B12 , folic acid, carnitine, etc.), and a hardly digestible oligosaccharide containing galactose (raffinose, lactulose, soybean oligosaccharide, galactooligosaccahride, melibiose, etc.), as active components.

Journal ArticleDOI
TL;DR: Testing 53 isolates of this dermatophyte for their ability to assimilate several carbon sources, for keratinase, proteinase, phospholipase, lipase and desoxiribonuclease secretions, and for their susceptibility to the antifungals fluconazole, ketoconazole and itraconazole suggest that significant phenotypic variations exist among T. rubrum isolates.
Abstract: To characterize possible Trichophyton rubrum phenotypes, which circulate in two Brazilian localities, we tested 53 isolates of this dermatophyte for their ability to assimilate several carbon sources, for keratinase, proteinase, phospholipase, lipase and desoxiribonuclease (DNase) secretions, and for their susceptibility to the antifungals fluconazole, ketoconazole and itraconazole. For each method, the isolates were submitted to similarity analysis and the methods were evaluated for their discriminatory indexes. None of the isolates were capable of assimilating arabinose, dulcitol, lactose, melibiose, ribose and xylose, while all of the isolates assimilated maltose, sucrose and sorbitol. However, adonitol, cellobiose, dextrin, erythritol, fructose, galactose, inulin, mannitol, mannose, raffinose, rhamnose and trehalose were assimilated by some isolates but not by others. All isolates secreted keratinase and DNase, while none secreted phospholipase. Proteinase and lipase were secreted only by some isolates. All but four isolates were resistant to fluconazole, most of them were sensitive to ketoconazole and all were sensitive to itraconazole. Carbohydrate assimilation was the method that presented the highest discriminatory index, and also the method that displayed the largest number of biotypes. Taken together, these data suggest that significant phenotypic variations exist among T. rubrum isolates. They seem to occur independently from their geographic origins.

Journal Article
TL;DR: The morphology and biochemical characteristics of patho-genic bacteria that are found in infected shrimps in the intensive cu1ture pond are dealt with and the iso-lated bacterium is Vibrio parahaemolyticus.
Abstract: The paper deals with the morphology and biochemical characteristics of patho-genic bacteria that are found in infected shrimps in the intensive cu1ture pond. The bacte-ria are isolated and purified from haemolymph and hepatopancreas of the infectedshrimps, and the pathogenicity of isolated bacteria and the same infected symptoms arefound after the isolated bacteria infect shrimps. Also the bacteria are isolated and puri-fied from haemolymph and hepatopancreas of the re--infected shrimps. The isolated andre--iso1ated bacteria in this study all are gram negative, short rods with a single polar fla-gellum, resistant to O/129, oxidase and catalase positive, salt requirement, growing wellin 3 %, 6 %,8 % NaCl and on TCBS, but no growth in l0% NaCl. The bacterium can uti-lize citrate, mannitol, fructose, galactose. They don't ferment lactose, inositol, sorbitol,xylose and melibiose. V--P reaction, sulfide production, arginine dighdrolase and tryptopl-can deaminase of this bacterium is negative. Bacteriological identification shows the iso-lated bacterium is Vibrio parahaemolyticus.

Journal ArticleDOI
TL;DR: In this article, a preparation procedure for the synthesis of N-glycyl-β-glycopyranosylamines, derivatives of monosaccharides (d-galactose,d-mannose,l-fucose, and N-acetyl-d-glucosamine) and disaccharide derivatives (lactoses, melibiose, cellobiose and maltose) was developed.
Abstract: A convenient preparative procedure was developed for the synthesis ofN-glycyl-β-glycopyranosylamines, derivatives of monosaccharides (d-galactose,d-mannose,l-fucose, andN-acetyl-d-glucosamine) and disaccharides (lactose, melibiose, cellobiose, and maltose). These compounds were demonstrated to be useful for the preparation of glycoconjugates of biologically active compounds containing the carboxy group (nicotinic, orotic, kynurenic, and indoleacetic acids). Synthetic pathways were developed for conversions ofN-glycyl-β-glycopyranosylamines into derivatives containing the carboxy group with the use of malonic andl-tartaric acid derivatives.