Showing papers on "Melibiose published in 2005"

Clostridium carboxidivorans sp. nov., a solvent-producing clostridium isolated from an agricultural settling lagoon, and reclassification of the acetogen Clostridium scatologenes strain SL1 as Clostridium drakei sp. nov.

Abstract: A novel solvent-producing, anaerobic clostridium, strain P7T, was isolated from sediment from an agricultural settling lagoon after enrichment with CO as the substrate. The metabolism of this Gram-positive, motile, spore-forming rod was primarily acetogenic. Acetate, ethanol, butyrate and butanol were the end-products of metabolism. Strain P7T grew on CO, H2/CO2, glucose, galactose, fructose, xylose, mannose, cellobiose, trehalose, cellulose, starch, pectin, citrate, glycerol, ethanol, propanol, 2-propanol, butanol, glutamate, aspartate, alanine, histidine, asparagine, serine, betaine, choline and syringate as sole substrates. Growth was not supported by methanol, formate, d-arabinose, fucose, lactose, melibiose, amygdalin, gluconate, lactate, malate, arginine, glutamine or vanillate. Nitrate reduction, production of indole, gelatin hydrolysis and aesculin hydrolysis were not observed. Analysis of the 16S rRNA gene sequence of the isolate showed that it was closely related to Clostridium scatologenes ATCC 25775T (99·7 % sequence similarity) and clostridial strain SL1T (99·8 % sequence similarity). Strain SL1 had been classified as a strain of C. scatologenes. However, DNA–DNA reassociation analysis showed that both strain P7T and strain SL1 represented novel clostridial species. It is proposed that strain P7T (=ATCC BAA-624T=DSM 15243T) be classified as the type strain of Clostridium carboxidivorans sp. nov. and that strain SL1T (=ATCC BAA-623T=DSM 12750T) be reclassified as the type strain of Clostridium drakei sp. nov.

Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30 1333 keV

Abstract: The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30–1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

Substrate-induced conformational changes of melibiose permease from Escherichia coli studied by infrared difference spectroscopy.

Abstract: Fourier transform infrared difference spectroscopy has been used to obtain information about substrate-induced structural changes of the melibiose permease (MelB) from Escherichia coli reconstituted into liposomes. Binding of the cosubstrate Na(+) gives rise to several peaks in the amide I and II regions of the difference spectrum Na(+).MelB minus H(+).MelB, that denote the presence of conformational changes in all types of secondary structures (alpha-helices, beta-sheets, loops). In addition, peaks around 1400 and at 1740-1720 cm(-1) are indicative of changes in protonation/deprotonation or in environment of carboxylic groups. Binding of the cosubstrate Li(+) produces a difference spectrum that is also indicative of conformational changes, but that is at variance as compared to that induced by Na(+) binding. To analyze the following transport steps, the melibiose permease with either H(+), Na(+), or Li(+) bound was incubated with melibiose. The difference spectra obtained by subtracting the spectrum cation.MelB from the respective complex cation.melibiose.MelB were roughly similar among them, but different from those induced by cation binding, and more intense. Therefore, major conformational changes that are induced during melibiose binding/substrate translocation, like those denoted by intense peaks at 1668 and 1645 cm(-)(1), are similar for the three cotransporting cations. Changes in the protonation state and/or in the environment of given carboxylic residues were also induced by melibiose-MelB interaction in the presence of cations.

Purification and characterization of an alpha-galactosidase from Aspergillus fumigatus

Abstract: Aspergillus fumigatus secreted invertase (b-fructofuranosidase) and a-galactosidase enzymatic activities able to hydrolyzing raffinose oligosaccharides (RO). a-Galactosidase was induced by galactose, melibiose and raffinose, but galactose was the most efficient inducer. It was purified by gel filtration and two ion exchange chromatographies and showed Mw of 54.7 kDa. The purified enzyme showed maximal activity against p-nitrophenyl-a-D-galactopyranoside (pNPGal) at pH 4.5-5.5 and 55 °C, and retained about 80% of the original activity after incubation for 90 minutes at 50oC. The KM for pNPGal was 0.3 mM. Melibiose was hydrolyzed by the enzyme but raffinose was very poor substrate.

Cloning and expression of the gene encoding Streptomyces coelicolor A3(2) α-galactosidase belonging to family 36

Abstract: The α-galactosidase gene of Streptomyces coelicolor A3(2) was cloned, expressed in Escherichia coli and characterized. It consisted of 1497 nucleotides encoding a protein of 499 amino acids with a predicted molecular weight of 57,385. The observed homology between the deduced amino acid sequences of the enzyme and α-galactosidase from Thermus thermophilus was over 40%. The α-galactosidase gene was assigned to family 36 of the glycosyl hydrolases. The enzyme purified from recombinant E. coli showed optimal activity at 40 °C and pH 7. The enzyme hydrolyzed p-nitrophenyl-α-D-galactopyroside, raffinose, stachyose but not melibiose and galactomanno-oligosaccharides, indicating that this enzyme recognizes not only the galactose moiety but also other substrates.

Biochemical and catalytic properties of two β-glycosidases purified from workers of the termite Macrotermes subhyalinus (Isoptera: Termitidae)

Abstract: Two s-glycosidases were purified from the termite Macrotermes subhyalinus (Rambur) workers by chromatography on gel filtration, ion exchange and hydrophobic interaction columns. The preparations were shown to be homogeneous on Polyacrylamide gel. Both enzymes have a similar molecular mass (68 KDa) and optimum pH (5.4) but differ in optimal temperature and thermal stability. The s-glycosidases preferred s-fucosides to s-glucosides, s-galactosides and s-xylosides, and hydrolysed glucose-glucose-s-(l-4) linkages better than s-(l-3), s-(l-2) and s-(l-6) linkages. They did not hydrolyse saccharides such as melibiose, sucrose, lactose, xylobiose, melizitose, stachyose, lactose, raffinose, laminarin, arabinogalactan, carboxymethylcellulose, inulin, lichenan and starch. s-Glycosidase A and s-glycosidase B of M. subhyalinus workers are capable of catalysing transglucosylation reactions. The yields of glucosylation of hydroxyamino acid derivatives and phenylethanol, catalysed by the two enzymes in the presence of cellobiose as glucosyl donor, were lower than those reported previously with conventional sources of s-glycosidases. In addition, the optimum pH is different for the hydrolysis and trans glucosylation reactions.On the basis of this work, it is proposed that the physiological role of s-glycosidase A and s-glycosidase B of M. subhyalinus workers is the digestion of di- and oligosaccharides derived from hemicelluloses and celluloses.

Purification, cloning, and properties of α-galactosidase from Saccharopolyspora erythraea and its use as a reporter system

Abstract: An α-galactosidase from the erythromycin-producing bacterium Saccharopolyspora erythraea was purified to near homogeneity. The enzyme has an apparent molecular mass of 45 kDa as determined by SDS-PAGE. The pH optimum, Km for p-nitrophenyl-α-d-glucopyranoside (pNPαG), Km for melibiose and the Vmax are similar to those of other studied α-galactosidase enzymes. The N-terminal amino-acid sequence of this protein was determined. PCR amplification was used to generate a 640-bp product using oligonucleotide primers based on the N-terminal amino-acid sequence and a downstream region that is conserved in other related α-galactosidase enzymes. This fragment was used as a probe to clone the α-galactosidase gene, designated melA, from a S. erythraea lambda phage chromosomal library. S. erythraea appears to possess an unique α-galactosidase enzyme, encoded by melA, that can utilize galactopyranosides as carbon sources. Furthermore, the ability to use the product of melA as a reporter enzyme in S. erythraea has been demonstrated. The α-galactosidase uses the substrates 5-bromo-4-chloro-3-indoyl-α-d-galactosidase (X-α-gal) on agar media and pNPαG in liquid media.

Purification and Characterization of an α-Galactosidase from Aspergillus fumigatus

Abstract: Aspergillus fumigatus secreted invertase (β-fructofuranosidase) and α-galactosidase enzymatic activities able tohydrolyzing raffinose oligosaccharides (RO). α-Galactosidase was induced by galactose, melibiose and raffinose,but galactose was the most efficient inducer. It was purified by gel filtration and two ion exchangechromatographies and showed Mw of 54.7 kDa. The purified enzyme showed maximal activity against p-nitrophenyl-α-D-galactopyranoside (pNPGal) at pH 4.5-5.5 and 55 °C, and retained about 80% of the originalactivity after incubation for 90 minutes at 50oC. The KM for pNPGal was 0.3 mM. Melibiose was hydrolyzed by theenzyme but raffinose was very poor substrate.Key words: Aspergillus fumigatus, α-galactosidase, raffinose oligosaccharides * Auth or for cr espo nd INTRODUCTION The α-galactosidases (α-D-galactosidegalactohydrolase, EC 3.2.1.22) are a group ofexotype carbohydrases which catalyze thecleavage of terminal α-1,6-linked galactosylresidues from a wide range of substrates, includinglinear and branched oligosaccharides,polysaccharides and synthetic substrates such as ρ-nitrophenyl-α-D-galactopyranoside (Dey andPridman, 1972). α-Galactosidases have a numberof biotechnological applications: in beet sugarindustry, these enzymes are used to removeraffinose from beet molasses and to increase theyield of sucrose (Shibuya et al., 1995); they arealso used to improve the gelling properties ofgalactomannans to be used as food thickeners(Bulpin et al., 1990) and to degrade the raffinosefamily sugars (raffinose, stachyose andverbascose) in food and feed materials such assoya meal or soya milk (Guimaraes et al., 2001). The raffinose oligosaccharides (RO), speciallyraffinose and stachyose, are considered the majorfactors responsible for flatulence after ingestion ofsoybean or other legumes. The enzymic hydrolysisof the RO, therefore, may be of biotechnologicalinterest. The hydrolysis of the RO may beaccomplished by the α-galactosidase, invertase orboth. The α-galactosidase cleaves the α-1,6linkage, joining the galactosyl residue to sucrose,yielding galactose and sucrose, while the invertasehydrolyses the α-1,2 linkage, producing melibiose

Characterization of α-Galactosidase gene from Leuconostoc mesenteroides SY1

Abstract: Leuconostoc mesenteroides SY1, an isolate from kimchi, was able to ferment α-galactosides, such as melibiose and raffinose. α-Galactosidase (a-Gal) activity was higher in cells grown on melibiose and raffinose than cells grown on galactose, sucrose, and fructose. α-Gal activity was not detected in cells grown on glucose, indicating the operation of carbon catabolite repression (CCR). A 6 kb DNA fragment was PCR amplified using a primer set based on the nucleotide sequence of a putative α-galactosidase gene (aga) from L. mesenteroides ATCC 8293. Nucleotide sequencing of the 6 kb fragment confirmed the presence of aga and other genes involved in the galactosides utilization, and the gene order was galR (transcriptional regulator)-aga-galK (galactokinase)-galT (galactose-1-phosphate uridylyltransferase). Northern blotting experiment showed that aga, galK, and galT constituted the same operon, that the transcription was induced by galactosides, such as melibiose and raffinose, whereas galR was independently transcribed as a monocistronic gene, and that the level of transcription was fairly constant. The aga was overexpressed in E. coli BL21(DE3) using pET26b(+) vector, and α-Gal was accumulated in E. coli as an inclusion body.

Characterization of the $\alpha$ -Galactosidase Gene from Leuconostoc mesenteroides SY1

Abstract: Leuconostoc mesenteroides SY1, an isolate from kimchi, was able to ferment -galactosides, such as melibiose and raffinose. -Galactosidase (-Gal) activity was higher in cells grown on melibiose and raffinose than cells grown on galactose, sucrose, and fructose. -Gal activity was not detected in cells grown on glucose, indicating the operation of carbon catabolite repression (CCR). A 6 kb DNA fragment was PCR amplified using a primer set based on the nucleotide sequence of a putative -galactosidase gene (aga) from L. mesenteroides ATCC 8293. Nucleotide sequencing of the 6 kb fragment confirmed the presence of aga and other genes involved in the galactosides utilization, and the gene order was galR (transcriptional regulator)-aga-gaIK (galactokinase)-gaIT (galactose-1-phosphate uridylyltransferase). Northern blotting experiment showed that aga, gaIK, and gaIT constituted the same operon, that the transcription was induced by galactosides, such as melibiose and raffinose, whereas gaIR was independently transcribed as a monocistronic gene, and that the level of transcription was fairly constant. The aga was overexpressed in E. coli BL21 (DE3) using pET26b(+) vector, and -Gal was accumulated in E. coli as an inclusion body.

Melibiose operon expression system

Abstract: The present invention relates to vectors expressible in a host comprising the promoter region of the melibiose operon operably linked to a transcriptional unit comprising a nucleic acid sequence which is heterologous to said host, whereas the expression of said nucleic acid sequence is controlled by said promoter region of the melibiose operon. Also disclosed are, the use of said new vector for the regulated heterologous expression of a nucleic acid sequence in a prokaryotic host, an isolated and purified nucleic acid sequence expressible in a host comprising the promoter region of the melibiose operon operably linked to a transcriptional unit comprising a nucleic acid sequence which is heterologous to said host, whereas the expression of said nucleic acid sequence is controlled by said promoter region of the melibiose operon, a prokaryotic host transformed with said vector or said isolated and purified nucleic acid sequence, and a method for producing a polypeptide in a host using said vector.

T cell immunomodulator comprising melibiose as active ingredient

Abstract: PROBLEM TO BE SOLVED: To improve immune strength by T cell immunomodulating effects in relation to a T cell immunomodulator effective in improving the immune strength. SOLUTION: An immunological improving agent, the T cell immunomodulator and an oral immunological tolerance inducer each comprising melibiose as an active ingredient are provided. The melibiose has excellent T cell immunomodulating actions as compared with raffinose and is suitable for oral administration in aspects of a mouth melting feeling or taste. COPYRIGHT: (C)2006,JPO&NCIPI

Melibiose operon expression system

Abstract: The present invention relates to new vectors expressible in a host comprising the promoter region of the melibiose operon operably linked to a transcriptional unit comprising a nucleic acid sequence which is heterologous to said host, whereas the expression of said nucleic acid sequence is controlled by said promoter region of the melibiose operon Also disclosed are, the use of said new vector for the regulated heterologous expression of a nucleic acid sequence in a prokaryotic host, an isolated and purified nucleic acid sequence expressible in a host comprising the promoter region of the melibiose operon operably linked to a transcriptional unit comprising a nucleic acid sequence which is heterologous to said host, whereas the expression of said nucleic acid sequence is controlled by said promoter region of the melibiose operon, a prokaryotic host transformed with said vector or said isolated and purified nucleic acid sequence, and a method for producing a polypeptide in a host using said vector

Method of glucosyl transfer

Abstract: A novel method of forming, through an enzymatic reaction, a polyalcohol having glucosyl transferred, glucuronic acid having glucosyl transferred and a glucose 6-position sugar derivative having glucosyl transferred. There is provided a method of glucosyl transfer to a polyalcohol, glucuronic acid and a glucose 6-position sugar derivative, characterized in that trehalose phosphorylase acts on a sugar compound containing glucose as a constituent sugar as well as at least one polyalcohol selected from among inositol, ribitol, erythritol and glycerol, glucuronic acid and/or its salt, and/or at least one glucose 6-position sugar derivative selected from among isomaltose, gentibiose, melibiose, isomaltotriose and isopanose.

Chain Elongation of Primary Alcohols of Carbohydrates.

Abstract: The chain elongation of primary alcohol of saccharides (α- d -ribose, α- d -glucose, α- d -mannose) and a disaccharide (α- d -melibiose) has been achieved via a Mitsunobu reaction using bis(2,2,2-trifluoroethyl) malonate as nucleophile.

Basic nutritional investigation Promotive effects of non-digestible disaccharides on rat mineral absorption depend on the type of saccharide

Abstract: Objective: We examined the effects of feeding non-digestible disaccharides, difructose anhydride III (DFAIII), maltitol, melibiose and, cellobiose, on calcium, magnesium, and iron absorption in comparison with fructo-oligosaccharide (FOS) in normal and ovariectomized rats. Methods: In experiment 1, six groups of male Sprague-Dawley rats were fed a control diet (100 g of cellulose/kg of diet), test diets containing 30 g of FOS, or the four non-digestible disaccharides in place of the cellulose in the control diet for 4 wk. In experiment 2, two groups of female Sprague-Dawley rats (sham or ovariectomized) were assigned to one of four subgroups and fed the control or test diet containing FOS, DFAIII, and melibiose for 5 wk. Feces and cecal contents were collected to evaluate mineral absorption and cecal fermentation. Results: In experiment 1, calcium absorption in all the disaccharides groups except the cellobiose group, magnesium absorption in all test diet groups, and iron absorption in the FOS, DFAIII, and melibiose groups were higher than those in the control group. In ovariectomized rats (experiment 2), calcium absorption in the DFAIII and melibiose groups, magnesium absorption in all test diet groups, and iron absorption in the DFAIII group alone were higher than those in the control group. Cecal organic acids were positively and pH was negatively correlated with the absorption of these minerals, although the effects varied. Conclusion: Non-digestible disaccharides increase calcium, magnesium, and iron absorption in normal and ovariectomized rats; however, the effects depend on the disaccharide tested, a fact that may be partly associated with the cecal fermentation of these disaccharides. © 2005 Elsevier Inc. All rights reserved.