scispace - formally typeset
Search or ask a question

Showing papers on "Melibiose published in 2007"


Journal ArticleDOI
TL;DR: In this article, a novel and efficient way of producing aldonic acids was reported, where the selective catalytic oxidation of monosaccharides (arabinose, ribose, xylose, lyxose, mannose, rhamnose and glucose, glucose, galactose, N-acetyl-glucosamine) on Au, Pd and Pt catalysts was investigated.
Abstract: A novel and efficient way of producing of aldonic acids is reported. The selective catalytic oxidation of monosaccharides (arabinose, ribose, xylose, lyxose, mannose, rhamnose, glucose, galactose, N-acetyl-glucosamine) and disaccharides (lactose, maltose, cellobiose, melibiose) on Au, Pd and Pt catalysts was investigated. By using the gold catalyst, a total selectivity with respect to aldonic acids and a high catalytic activity for all investigated sugars was found. The reaction conditions for the production of maltobionic and lactobionic acids via oxidation on gold catalysts were optimised. A high long-term stability of two different gold catalysts for the oxidation of maltose and lactose, respectively, was found.

130 citations


Journal ArticleDOI
TL;DR: To the authors' knowledge, this is the first report of gene cloning for Penicillium α-galactosidase belonging to family 36 of glycosyl hydrolases and expression in Pichia pastoris.

47 citations


Journal ArticleDOI
TL;DR: This is the first report of purification and characterization of α-galactosidase from Rhizopus with some special properties, which may aid its utilization in the food and feed industries.

31 citations


Journal ArticleDOI
TL;DR: Two isolates of B. subtilis showed strong ability to degrade the oligosaccharides and they are seen as promising starter cultures for fermentation of African locust bean.
Abstract: In order to select starter cultures for controlled fermentation of African locust beans, Bacillus subtilis and B. pumilus from Soumbala were investigated for their ability to degrade arabinogalactan, stachyose, raffinose and sucrose—the main polysaccharides and oligosaccharides in African locust bean. The methods used were liquefaction of gels of galactomannan for screening, pH measurement and High Performance Anion Exhange Chromatography – Pulsed Amperometric Detection (HPAEC–PAD) for detailed degradation study of the carbohydrates. For B. subtilis isolates, liquefaction of galactomannan gels was observed and HPAEC–PAD showed that arabinogalactan and stachyose were partially degraded while raffinose was fully degraded after 48 h of fermentation. Melibiose, fructose and traces of galactose were detected as residual sugars. For B. pumilus isolates much weaker degradation of the carbohydrates was observed. Two isolates of B. subtilis showed strong ability to degrade the oligosaccharides and they are seen as promising starter cultures for fermentation of African locust bean.

26 citations


Journal ArticleDOI
TL;DR: Soybeans were soaked for 24h in tap water at 30°C in preparation for tempe fermentation, and concentrations of mono-, di-, and oligosaccharides in the beans and in the soak-water were determined by the activity of invertases and α-galactosidases endogenous to the beans, diffusion of the sugars into and out of the bean, and the species of micro-organism growing in the soaking-water as mentioned in this paper.
Abstract: Summary Soybeans were soaked for 24h in tap water at 30°C in preparation for tempe fermentation. Soaking was conducted under conditions that give a microbial fermentation, and in the presence of antibiotics where microbial growth was inhibited. Sucrose, stachyose and raffinose were the main di- and oligosaccharides in the beans, and their concentrations decreased by 84, 65 and 50%, respectively, during soaking. Glucose, fructose and galactose were found in the soak-water along with lesser amounts of sucrose, melibiose, raffinose and stachyose. Glucose was the main substrate for microbial growth in the soak-water. The concentrations of mono-, di-and oligosaccharides in the beans and in the soak-water were determined by the activity of invertases and α-galactosidases endogenous to the beans, diffusion of the sugars into and out of the bean, and the species of micro-organism growing in the soak-water.

23 citations


Journal ArticleDOI
TL;DR: Two putative α-galactosidase genes from rice belong to glycoside hydrolase family 27 and catalyzes efficient degalactosylation of galactomannans, such as guar gum and locust bean gum.
Abstract: Two putative α-galactosidase genes from rice (Oryza sativa L. var. Nipponbare) belonging to glycoside hydrolase family 27 were cloned and expressed in Escherichia coli. These enzymes showed α-galactosidase activity and were purified by Ni Sepharose column chromatography. Two purified recombinant α-galactosidases (α-galactosidase II and III; α-Gal II and III) showed a single protein band on SDS–PAGE with molecular mass of 42 kDa. These two enzymes cleaved not only α-D-galactosyl residues from the non-reducing end of substrates such as melibiose, raffinose, and stachyose, but also liberated the galactosyl residues attached to the O-6 position of the mannosyl residue at the reducing-ends of mannobiose and mannotriose. In addition, these enzymes clipped the galactosyl residues attached to the inner-mannosyl residues of mannopentaose. Thus, α-Gal II catalyzes efficient degalactosylation of galactomannans, such as guar gum and locust bean gum.

23 citations


Journal ArticleDOI
TL;DR: It is suggested that dietary melibiose strongly affected the Th cell responses to an ingested antigen, and the potential ofmelibiose to enhance the induction of oral tolerance is demonstrated.
Abstract: We examined how dietary melibiose affected the T-helper (Th) cell responses induced by an orally fed antigen in ovalbumin (OVA)-specific T cell receptor transgenic mice (OVA 23-3). Dietary melibiose markedly decreased the Th2 type responses as shown by a significant decrease in the interleukin (IL)-4 production and T cell proliferative response induced by sensitization from the 7-d oral administration of OVA. It was additionally observed that the Th1 type responses tended to decrease. We therefore examined the effect of melibiose feeding on the induction of immunological tolerance induced by the oral administration of an antigen (oral tolerance). The Th cell responses induced in BALB/c mice by subcutaneous immunization with OVA were suppressed by the prior oral administration of OVA. Such responses in the OVA-fed and immunized mice were further diminished by dietary melibiose. These results suggest that dietary melibiose strongly affected the Th cell responses to an ingested antigen, and further demonstrate the potential of melibiose to enhance the induction of oral tolerance.

21 citations


Journal ArticleDOI
TL;DR: An extracellular α-d -galactosidase from Talaromyces flavus CCF 2686 with extremely broad and unusual acceptor specificity is produced exclusively in the presence of the specific inducer—6-deoxy- d -glucose (quinovose).

20 citations


Journal ArticleDOI
TL;DR: In this article, an alternative cotransport mechanism is proposed where His-322 imidazolium, positioned in the central pore equidistant (5-7 A) between six charged amino acids, Arg-302 and Lys-319 opposing Glu-269, Glu/325, Asp-237, and Asp/240, transfers a proton transiently to an H-bonded lactose hydroxyl group.

18 citations


Journal ArticleDOI
TL;DR: The purified enzyme was active toward various substrates, including galactose, dihydroxyacetone, guar gum, lactose, melibiose, methyl‐galactopyranoside, and raffinose, but SDS was an inhibitor but EDTA, Tween 80, NH4+, Na+, Mg2+, K+, and glycerol were not.
Abstract: Extra-cellular production of a novel galactose oxidase from Fusarium acuminatum using submerged fermentation was studied. Glucose (1.0% w/v) was used as the sole carbon source. Maximum galactose oxidase production (approximately 4.0 U/ml) was obtained when fermentation was carried out at 25 degrees C, with orbital shaking (100 rpm) and an initial medium of pH 7.0, for 96 h, using a 2% (v/v) inoculum made from a homogenized four-day-old liquid culture, in the presence of copper, manganese, and magnesium. The enzyme was purified by one-step affinity chromatography, with a recovery of 42% of the initial activity. The purified enzyme ran as a single band of 66 kDa in SDS-PAGE. Optimal pH and temperature for the enzyme activity were 8.0 and 30 degrees C, respectively. The enzyme was thermoinactivated at temperatures above 60 degrees C. The purified enzyme was active toward various substrates, including galactose, dihydroxyacetone, guar gum, lactose, melibiose, methyl-galactopyranoside, and raffinose. SDS was an inhibitor but EDTA, Tween 80, NH(4)(+), Na(+), Mg(2+), K(+), and glycerol were not. The Michaelis-Menten constant (K(m)) for galactose was estimated to be 16.2 mM, while maximal velocity (V(max)) was 0.27 micromol of H(2)O(2) . ml(-1) . min(-1).

13 citations


Journal ArticleDOI
TL;DR: In this paper, the initial rates for monomyristoyl disaccharide formation were compared with the initial disacaride concentration normalized by the solubility of the disac-charide in the mixture.
Abstract: The condensation of trehalose, maltose, cellobiose, sucrose, turanose, palatinose, lactose and melibiose with myristic acid by a lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) from Candida antarctica was examined at 60 °C in a mixture of pyridine and 2-methyl-2-propanol (20/80 by vol.). The reactivity of trehalose was the highest among the tested disaccharides, and maltose and palatinose followed. Cellobiose and lactose were poor substrates for condensation. Condensation of all the disaccharides except for cellobiose and lactose with myristic acid was carried out at various initial disaccharide concentrations to estimate the initial reaction rate. Plots of the initial rates for monomyristoyl disaccharide formation versus the initial disaccharide concentration normalized by the solubility of the disaccharide in the mixture indicated that palatinose was the best substrate, and that trehalose, turanose and maltose were the next best ones. The surface activity of the monoacyl disaccharides scarcely depended on the type of disaccharide. Copyright © 2007 Society of Chemical Industry

Journal Article
TL;DR: A 2.5 kb aga gene encoding alpha-galactosidase (alpha- Gal) from Leuconostoc mesenteroides SY1 was cloned into pSJE, an E. coli-LeuConostoc shuttle vector and results indicated that the heterologous aga was successfully expressed in L. citreum and its transcription was under the carbon catabolite repression (CCR).
Abstract: A 2.5 kb aga gene encoding alpha-galactosidase (alpha- Gal) from Leuconostoc mesenteroides SY1 was cloned into pSJE, an E. coli-Leuconostoc shuttle vector. The recombinant plasmid, pSJEaga, was introduced into Leuconostoc citreum KCTC3526 (ATCC49370) by electroporation. Transcription level of aga was the highest in cells grown on raffinose (1%, w/v) followed by cells grown on galactose, melibiose, fructose, glucose, and sucrose. Western blot using antibodies against alpha-Gal showed similar results to slot-blot results and enzyme activity measurements. All the results indicated that the heterologous aga was successfully expressed in L. citreum and its transcription was under the carbon catabolite repression (CCR).

Journal Article
TL;DR: The results show that the a-galactosidase is a novel one that is able to degrade natural substrates such as melibiose, raffinose and stachyose but not galactose-containing polysaccharides.
Abstract: An a-galactosidase-producing fungus was screened out of 26 filamentous fungi isolated from soil by us. Phylogenetic analysis based on the alignment of 18S rDNA sequences, combined with the morphological identification, indicated that the strain F63 was a member of the genus Penicillium. The a-galactosidase from Penicillium sp. F63 was purified to apparent homogeneity by ammonium sulfate precipitation, ion-exchange and gel filtration chromatography. The molecular size of the purified enzyme is approximately 82kDa estimated by SDS-PAGE. The a-galactosidase has an optimum pH of 5.0 and an optimum temperature of 45 degrees C. The enzyme is stable between pH5.0 and 6.0 below 40 degrees C. The a-galactosidase activity is slightly inhibited by Ag+ , which is dissimilar to other a-galactosidases. Kinetic studies of the a-galactosidase showed that the Km and the Vmax for pNPG are 1.4mmol/L and 1.556mmol/L. min(-1) x mg- 1, respectively. The enzyme is able to degrade natural substrates such as melibiose, raffinose and stachyose but not galactose-containing polysaccharides. The alpha-galactosidase was identified by MALDI-TOF-MS and its inner peptides were sequenced by ESI-MS/MS. The results show that the a-galactosidase is a novel one.

Journal ArticleDOI
TL;DR: Galactose was the most effective carbon source for α-galactosidase production followed by other sugars containing α-Galactoside bounds, such as melibiose, stachyose and raffinose, and yeast extract was the best nitrogen source for enzyme production from local isolated Bacillus circulans.
Abstract: α- Galactosidase was detected in the culture media of Bacillus circulans isolated from soil of (plants Island in Aswan). The optimum condition for growth and enzyme production were determined where the optimum pH was 6.5 to 7and incubation temperatures was 35 to 40oC. Maximum activity of α-galactosidase in the production media was found after 48 hours (2.21 U/ml) followed by decreasing in activity at the 3rd day (0.860 U/ml). No activity was detected at the 4th day of incubation. Galactose was the most effective carbon source for α-galactosidase production followed by other sugars containing α-galactoside bounds, such as melibiose, stachyose and raffinose. Yeast extract in addition, was the best nitrogen source for enzyme production from local isolated Bacillus circulans . New Egyptian Journal of Microbiology Vol. 17 (2) 2007: pp. 224-232

Journal ArticleDOI
TL;DR: Purified -galactosidase was obtained after sonication of harvested cell pellet followed by DEAE-Sephadex A-50 and Mono Q anion exchange chromatography and liberated galactose from melibiose, raffinose, and stachyose.
Abstract: Lactobacillus salivarius subsp. salivarius CNU27 possessed a high level of -galactosidase activity. Purified -galactosidase was obtained after sonication of harvested cell pellet followed by DEAE-Sephadex A-50 and Mono Q anion exchange chromatography. The specific activity of the purified enzyme was 8,994 units/mg protein which is 17.09 times higher than that in crude extract. The native enzyme was a monomer with a molecular mass of 56,397.1 dalton. The optimum temperature and pH for the enzyme were and 6.0, respectively. The enzyme was stable between 25 and . However, -galactosidase activity was lost rapidly below pH 4.5 and above pH 8.5. The enzyme activity decreased to 6.73% and 4.30% of the original activity by addition of and , respectively. Other metal compounds did not affect the enzyme activity significantly. The enzyme liberated galactose from melibiose, raffinose, and stachyose. The rate of substrates hydrolysis was measured by HPLC. Raffinose, stachyose and melibiose were completely decomposed after 24 hr at .

Journal Article
TL;DR: In this article, the compositions of free sugars in soybean seeds and soybean oligosaccharide syrup were investigated through high performance liquid chromatography and enzymatic hydrolysis with β-galactosidase.
Abstract: The compositions of free sugars in soybean seeds and soybean oligosaccharide syrup were investigated through high performance liquid chromatography and enzymatic hydrolysis with β-galactosidase. A Sugar-D column was used with aceto-nitrile-water solution (75:25, V/V) as the mobile phase at a flow rate of 1 ml/min, and a refractive index detector was used for the detection of sugars. Under such conditions, it ensured good separation for the sugars with stable baseline. The relative standard deviations and recovery rates were between 1.0% to 2.0% and 96.7% to 106.7%, respectively, for fructose, sucrose, melibiose, raffinose, and stachyose. Through the analysis, we found that both soybean seed and soybean oligosaccharide syrup contained fructose, sucrose, melibiose, raffinose, stachyose, and two unknown substances, while the latter also contained glucose (galactose) and another unknown compound which was inferred as manninotriose based on the result of α-galactosidase degradation. The growth activator of bifidobacterial in soybean oligosaccharide syrup was mainly manninotriose and stachyose.

01 Jan 2007
TL;DR: The α-galactosidase Mel4A gene of Bacillus halodurans was recombinantly expressed in Escherichia coli, purified and characterized, and it was found that this enzyme preferred small saccharides to highly polymerized galactomannans.
Abstract: The α-galactosidase mel4A (previously called melA) gene of Bacillus halodurans was recombinantly expressed in Escherichia coli, purified and characterized. The mel4A gene consists of 1305 nucleotides encoding a protein of 434 amino acids with a predicted molecular weight of 49,761. According to its primary structure as deduced from the nucleotide sequence of the gene, Mel4A was assigned to family 4 of glycoside hydrolases. Almost all of the enzyme was produced as inclusion bodies at 37C in E. coli. In order to reduce the expression level, cultivation temperature was decreased to 20C so that the enzyme could be collected from soluble fraction. Recombinant α-galactosidase Mel4A was purified to homogeneity in a single step using His-binding metal affinity chromatography. B. halodurans Mel4A has the unusual property, i.e., absolutely depending on NAD and Mn for activity. Co and Ni also activated Mel4A, albeit less efficiently than Mn. In addition, Mel4A activity required reducing condition which met by the addition of dithiothreitol (DTT). In the presence of all cofactors, optimum activity was achieved at 37C and pH 7.4. The enzyme hydrolyzed p-nitrophenyl-α-D-galactopyranoside, melibiose, raffinose, and stachyose but not guar gum, indicating that this enzyme preferred small saccharides to highly polymerized galactomannans. Western immunoblots of intracellular and extracellularproteins of B. halodurans revealed that raffinose induced the expression of intracellular Mel4A of B. halodurans. This bacterium was also able to utilize guar gum as the carbon source, but Western blot analysis indicated that the production of Mel4A was not enhanced by the addition of guar gum.