Showing papers on "Melibiose published in 1984"
TL;DR: The nucleotide sequence of the melB gene coding for the melibiose carrier in Escherichia coli has been determined and the predicted carrier protein is highly hydrophobic (70% nonpolar amino acid residues).
170 citations
TL;DR: The data demonstrate that the G AL80 protein is a purely negative regulator, the GAL80 protein does not mediate carbon catabolite repression, and theGAL4 protein is not simply an antagonizer of GAL 80-mediated repression.
Abstract: In Saccharomyces cerevisiae, the transcriptional expression of the galactose-melibiose catabolic pathway genes is under the control of at least three regulatory genes, GAL4, GAL80, and GAL3. We have isolated the GAL80 gene and have studied the effect of a null mutation on the carbon-controlled regulation of the MEL1 and GAL cluster genes. The null mutation was achieved in vivo by replacing the chromosomal wild-type GAL80 allele with an in vitro-created GAL80 deletion-disruption mutation. Enzyme activities and RNA levels for the GAL cluster and MEL1 genes were constitutively expressed in the null mutant strain grown on glycerol-lactate and were higher than in the isogenic wild-type yeast strain when compared after growth on galactose. Carbon catabolite repression of the GAL cluster and MEL1 genes, which occurs at the level of transcription, is retained in the null mutant. Deletion of the GAL80 gene in a gal4 cell does not restore GAL cluster and MEL1 gene expression. The data demonstrate that (i) the GAL80 protein is a purely negative regulator, (ii) the GAL80 protein does not mediate carbon catabolite repression, and (iii) the GAL4 protein is not simply an antagonizer of GAL80-mediated repression.
120 citations
TL;DR: Evidence is presented that the MEL1 gene encodesalpha-galactosidase and that mel0 is a naturally occurring allele which lacks the alpha-galactsidase-coding sequences.
Abstract: The MEL1 gene in Saccharomyces cerevisiae is required for the production of alpha-galactosidase and for the catabolism of melibiose. Production of alpha-galactosidase is induced by galactose or melibiose and repressed by glucose. Inducibility is controlled by the positive and negative regulatory proteins GAL4 and GAL80, respectively. We have cloned the MEL1 gene to study its transcriptional expression and regulation. Evidence is presented that the MEL1 gene encodes alpha-galactosidase and that mel0 is a naturally occurring allele which lacks the alpha-galactosidase-coding sequences. RNAs prepared from wild-type cells and from cells carrying either the noninducible gal4-2 or GAL80S-100 allele grown on three different carbon sources were examined by Northern hybridization analyses. In wild-type cells under noninducing conditions, such as growth on glycerol-lactic acid, the MEL1 transcript was detected at a basal level which was 1 to 2% of the fully induced level. The basal level of expression was diminished in cells carrying the gal4-2 mutant allele but not in cells carrying the GAL80S-100 allele. The basal and induced RNA levels are repressed by glucose. Size determinations of the MEL1 transcripts detected in glycerol-lactic acid- and galactose-grown cells provided no evidence for two distinct transcripts.
86 citations
TL;DR: Tsuchiya et al. as mentioned in this paper identified hybrid plasmids carrying the melibiose operon of Escherichia coli in a colony bank of Clarke and Carbon, and several DNA segments were subcloned into pBR322.
74 citations
TL;DR: Results indicate that nonanoyl- and decanoyL-N-methylglucamide are useful detergents for solubilization and reconstitution of membrane proteins.
Abstract: Alkanoyl-N-methylglucamides, nonionic detergents, were utilized to solubilize membrane proteins of Escherichia coli and were used to reconstitute them into liposomes. First, critical micelle concentrations (CMC) of nonanoyl-N-methylglucamide and decanoyl-N-methylglucamide were determined to be 25 mM and 7 mM, respectively, by photometric assay. Then solubilization and reconstitution of the melibiose transport carrier were performed using these detergents at concentrations above the CMC. Melibiose counterflow activity was observed with the proteoliposomes reconstituted from the extracted proteins and phospholipids. The proton-translocating ATPase complex (F1-F0) was also solubilized with these detergents. These results indicate that nonanoyl- and decanoyl-N-methylglucamide are useful detergents for solubilization and reconstitution of membrane proteins.
49 citations
TL;DR: Yersinia pseudotuberculosis serogroup III is most frequently detected in healthy pigs, and melibiose-fermenting strains seem to be virulent for mice, but melibose-nonfermentsing strains showed no virulence for mice.
Abstract: Yersinia pseudotuberculosis serogroup III is most frequently detected in healthy pigs. Y. pseudotuberculosis strains were divided into two biogroups on the basis of their fermentation of melibiose. Melibiose-fermenting strains were distributed in all the hosts and serogroups examined. Melibiose-nonfermenting strains were limited to serogroup III isolated from healthy pigs. Autoagglutination and calcium dependency were not related to fermentation of melibiose. Melibiose-fermenting strains seem to be virulent for mice, but melibiose-nonfermenting strains showed no virulence for mice.
35 citations
TL;DR: Two alpha-D-galactosidases produced by Aspergillus tamarii were purified from the mycelial extract by a procedure including chromatography on hydroxyapatite, DEAE- cellulose and ECTEOLA-cellulose, and each of these enzymes showed a single protein band corresponding to the alpha- D-galactsosidase activity when examined by polyacrylamide-gel electrophoresis.
Abstract: Two alpha-D-galactosidases (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) produced by Aspergillus tamarii were purified from the mycelial extract by a procedure including chromatography on hydroxyapatite, DEAE-cellulose and ECTEOLA-cellulose. Each of these enzymes showed a single protein band corresponding to the alpha-D-galactosidase activity when examined by polyacrylamide-gel electrophoresis. They catalysed the hydrolysis of o-nitrophenyl alpha-D-galactoside, melibiose, raffinose and stachyose, but did not attack the galactomannans. Their Mr values were respectively 265000 +/- 5000 and 254000 +/- 5000 by the method of Hedrick & Smith [(1968) Arch. Biochem. Biophys. 126, 155-164]. Polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate in each case showed a single protein band, with Mr 88000 and 77500 respectively. The purified enzymes contained carbohydrate, consisting of N-acetylglucosamine, mannose, glucose and galactose in the estimated molar proportions of 1:9:5:8 in alpha-galactosidase I.
35 citations
TL;DR: The relative retention times and detector responses of trimethylsilyl-oxzime derivatives of the components of soluble soy saccharides, up to pentasaccharide, on SP-2250 liquid phase are reported in this paper.
32 citations
TL;DR: A glucose‐dependent hemagglutinin, present in the serum of an apparently healthy donor, is shown to be a polyclonal IgM immunoglobulin with specificity for β‐D‐glucopyranose configuration, and antibodies are present in sera of all normal adults against erythrocytes coated with melibiose and N‐acetylmannosamine.
Abstract: A glucose-dependent hemagglutinin, present in the serum of an apparently healthy donor, is shown to be a polyclonal IgM immunoglobulin with specificity for beta-D-glucopyranose configuration. The antibody did not agglutinate erythrocytes coated with hexoses differing from glucose at C2, C3, or C4 positions or lacking the primary alcohol group at C6 position. The hemagglutination reaction, quantitated in a continuous flow system, was inhibited by the addition of 6-deoxyglucose, 5-thioglucose, 2-deoxyglucose, 2-aminoglucose or 3-0 methylglucose. D-glucose, in beta- but not in alpha-configuration, attached by a glycosidic bond to another glucose or to an aglycone, was also inhibitory. A cross-reactivity was demonstrated between glucose and 6-deoxyglucose by antibody absorption and elution techniques. The donor's serum contained independent antibodies that reacted with erythrocytes coated with melibiose, gentiobiose, cellobiose, or N-acetylmannosamine. Further investigation revealed that antibodies are present in sera of all normal adults against erythrocytes coated with melibiose and N-acetylmannosamine and with high frequency against erythrocytes coated with gentiobiose, L-rhamnose, cellobiose, D-mannose, lactose, or D-galactose.
25 citations
TL;DR: The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p-chloromercuribenzoate, galactose, and melibiose and the enzyme also seemed to catalyse a glycosyltransfer reaction.
Abstract: α-Galactosidase (EC 3.2. 1.22) from Pycnoporus cinnabarinus was purified by precipitation with ammoniumsulfate, column chromatographies on DEAE-SephadexA-50, Sephadex G-100, CMS ephadex C-50, and SP-Sephadex C-50, and isoelectric focusing. The purified enzyme was homogeneous on polyacrylamide disc gel electrophoresis, and the molecular weight was estimated to be about 210, 000 by gel filtration on Sephacryl S-200 and about 52, 000 by sodium dodecyl sulfate gel electrophoresis. The enzyme exhibited the optimum pH at 5.0 and was stable between pH 3 and 9. The optimumtemperature of the enzyme was 75°C. The enzymewas thermostable at pH 5.0 and completely lost its activity after heating at 90°C or at pH 3.5. The Michaelis constants were 0.31 mM for p-nitrophenyl α-D-galactoside, 0.80mM for melibiose, 2.16mM for raffinose, and 1.15mM for stachyose. The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p-chloromercuribenzoate, galactose, and melibiose. The enzyme also seemed to catalyse a glycosyltransfer reaction.
20 citations
TL;DR: The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p -chloromercuribenzoate, galactose, and melibiose and the enzyme also seemed to catalyse a glycos...
Abstract: α-Galactosidase (EC 3.2.1.22) from Pycnoporus cinnabarinus was purified by precipitation with ammonium sulfate, column chromatographies on DEAE-Sephadex A-50, Sephadex G-100, CM-Sephadex C-50, and SP-Sephadex C-50, and isoelectric focusing. The purified enzyme was homogeneous on polyacrylamide disc gel electrophoresis, and the molecular weight was estimated to be about 210,000 by gel filtration on Sephacryl S-200 and about 52,000 by sodium dodecyl sulfate gel electrophoresis. The enzyme exhibited the optimum pH at 5.0 and was stable between pH 3 and 9. The optimum temperature of the enzyme was 75°C. The enzyme was thermostable at pH 5.0 and completely lost its activity after heating at 90°C or at pH 3.5. The Michaelis constants were 0.31 mM for p -nitrophenyl α-D-galactoside, 0.80 mM for melibiose, 2.16mM for raffinose, and 1.15 mM for stachyose. The α-galactosidase activity was strongly inhibited by Ag+, Hg++, p -chloromercuribenzoate, galactose, and melibiose. The enzyme also seemed to catalyse a glycos...
TL;DR: Two molecular forms of the enzyme, designated as A and B, were eluted after SP-Sephadex C50–120 ion-exchange chromatography and the possible cause(s) of the deficiency of α- d -galactosidase activity in makapuno is discussed.
TL;DR: The results support the view that the alterations in the melibiose carrier and in the Na+(Li+)/H+ antiporter, observed in the mutants, are not genetically linked.
Abstract: Revertants that showed normal cation recognition for melibiose transport were isolated from mutants with altered cation recognition (W3133-2S and W3133-2T) of Escherichia coli. Although the original two mutants possessed a second alteration, an increased activity of the Na+(Li+)/H+ antiporter, the revertants, which possessed the normal melibiose carrier, still showed altered properties of the Na+(Li+)/H+ antiporter. These results support the view that the alterations in the melibiose carrier and in the Na+(Li+)/H+ antiporter, observed in the mutants, are not genetically linked.
TL;DR: The nucleotide sequence of the promoter region of the melibiose operon of E. coli was determined in this article and consensus sequences for the -35 region, the Pribnow box and the binding site for cyclic AMP receptor protein were found in this region.
TL;DR: In this paper, the kinetics of sorghum molasses and melibiose with dilute mineral acids and oxalic acid at relatively high temperatures were investigated. But it was shown that the second hydrogen atom does not significantly participate in the hydrolysis process.
Abstract: Investigations were carried out on the kinetics of hydrolyses of sorghum molasses with dilute mineral acids and oxalic acid and melibiose with oxalic acid at relatively high temperatures. Kinetic equations for hydrolysis of sorghum molasses and melibiose have been derived from the experimentally determined hydrolysis rate constants as functions of the acid concentration and temperature. It has been shown that the hydrolysis activity of oxalic acid is weaker than those of hydrochloric and sulfuric acid, and that the second hydrogen atom in oxalic acid does not significantly participate in hydrolysis.