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At least 433 records · Page 24Linked to original sources

PubMed1965

POSTNATAL DEVELOPMENT OF BETA-GALACTOSIDASE ACTIVITY IN THE SMALL INTESTINE OF THE RAT. EFFECT OF ADRENALECTOMY AND DIET.

1. beta-Galactosidase activity was studied in homogenates of the proximal and distal thirds of the small intestine from adult and infant rats. o-Nitrophenyl beta-d-galactoside served as the substrate. 2. Activity in suckling rats is highest in the distal part of the small intestine. 3. The pH optimum was 3.5 in the distal third of the small intestine in rats aged 5 and 15 days, whereas in the proximal third the maximum was not clearly defined. 4. Activity was higher in both thirds in newborn than in adult rats, expressed per wet wt. or per wt. of protein. In the proximal third activity continually decreases with age, whereas in the distal part there is a rise up to day 15 and then a sudden decrease. Total beta-galactosidase activity changes very little in the proximal third during postnatal development; the greatest changes occur in the distal third. 5. Adrenalectomy performed on day 15 postnatally slows down the decrease in beta-galactosidase activity, particularly in the distal part. 6. Feeding a lactose diet to infant rats from day 14 postnatally in the presence of the mother rat also slows down the decrease in beta-galactosidase activity and this is not found with a diet containing glucose and galactose instead of lactose.

Adrenalectomy↗

PubMed1990

Cloning of alpha- and beta-galactosidase genes from an extreme thermophile, Thermus strain T2, and their expression in Thermus thermophilus HB27.

The genes encoding thermostable alpha- and beta-galactosidases from an extremely thermophilic bacterium, Thermus strain T2, were cloned in Escherichia coli. The alpha-galactosidase gene was located just downstream from the beta-galactosidase gene. The genes were introduced into Thermus thermophilus HB27 with the aid of Thermus cryptic plasmid pTT8, and beta-galactosidases were expressed constitutively.

Cloning, Molecular↗

PubMed2001

trans-Sialidase catalyzed sialylation of beta-galactosyldisaccharide with an introduction of beta-galactosidase.

Introduction of beta-galactosidase into a trans-sialidase reaction, i.e. sialic acid transfer reaction from a donor substrate (alpha2,3-sialyllactose) to an acceptor substrate (beta-galactosyldisaccharide), could improve the yield of desired sialylated trisaccharide by hydrolyzing lactose, a byproduct from the donor. When trans-sialidase reaction was performed with stoichiometric amounts (2 mM) of alpha2,3-sialyllactose and Galbeta(1,3)GlcNAc, the yield of NeuAcalpha(2,3)Galbeta(1,3)GlcNAc increased from 45% to 75% by the coupling of Escherichia coli beta-galactosidase. Furthermore, by changing the substrate ratio in the coupled reaction, i.e. two-fold excess of alpha2,3-sialyllactose to Galbeta(1,3)GlcNAc, above 95% of yield was achieved based on the amount of Galbeta(1,3)GlcNAc. However, two-fold excess of Galbeta(1,3)GlcNAc to alpha2,3-sialyllactose in this reaction was more desirable for the purification of NeuAcalpha(2,3)Galbeta(1,3)GlcNAc, since complete consumption of alpha2,3-sialyllactose was achieved. Efficiency of the coupled reaction was affected by the specificity of beta-galactosidase for acceptor substrate. When Galbeta(1,6)GlcNAc was used as the acceptor, E. coli beta-galactosidase hydrolyzed Galbeta(1,6)GlcNAc as well as lactose in the coupled reaction, resulting in a significant decrease in the yield of desired sialylated trisaccharide. The conversion yield of the sialylation of Galbeta(1,6)GlcNAc could be improved by employing Bacillus circulans beta-galactosidase.

Journal Article↗

PubMed1992

The Role of beta-Galactosidases in the Modification of Cell Wall Components during Muskmelon Fruit Ripening.

The changes in activities of soluble beta-galactosidase and two forms of wall-bound beta-galactosidases extracted with NaCl and EDTA were investigated throughout the development of muskmelon (Cucumis melo L. cv Prince) fruits. DEAE-cellulose ion-exchange chromatography of soluble beta-galactosidase revealed the presence of two isoforms. Soluble isoform I was detected in all stages throughout the fruit development, whereas soluble isoform II appeared around 34 d after anthesis when fruit ripening initiated. Both NaCl- and EDTA-released beta-galactosidase activities also increased as ripening proceeded. The soluble and wall-bound forms behaved differently upon ion-exchange chromatography. Enzymological properties such as optimum pH, optimum temperature, K(m) values for p-nitrophenyl beta-d-galactopyranoside, and inhibition by metal ions were nearly similar in all forms. Molecular sizes of pectic polymers and hemicelluloses extracted from fruit mesocarp cell walls were shifted from larger to smaller polymers during ripening, as determined by gel filtration profiles. NaCl-released beta-galactosidase from cell walls of ripe fruits had the ability to degrade in vitro the pectin extracted from preripe fruit cell walls to smaller sizes of pectin similar to those that were observed in ripe cell walls in situ. Both soluble isoform I and II were able to degrade in vitro the 5% KOH-extractable hemicellulose from preripe fruit cell walls to sizes of molecules similar to those that were observed in ripe cell walls in situ. Soluble isoform I and the NaCl-released form from ripe fruits were able to modify in vitro 24% KOH-extractable hemicellulose from preripe cell walls to sizes of molecules similar to those that were observed in ripe fruits in situ.

Journal Article↗

PubMed1974

Evidence Against the Involvement of Galactosidase or Glucosidase in Auxin- or Acid-stimulated Growth.

Research on the mode of action of auxin in the promotion of growth has shown that auxin treatment leads to hydrogen ion secretion and wall acidification. It has recently been reported that auxin stimulates cell wall beta-galactosidase activity in Avena coleoptiles, presumably by causing cell wall acidification, since the pH optimum for the enzyme is about 5.0. It has been suggested that enhancement of beta-galactosidase and/or other glycosidase activity mediates growth promotion by auxin or low pH. This hypothesis was tested by examining the effect of inhibitors of beta-galactosidase and beta-glucosidase. Severe inhibition of measureable beta-galactosidase or beta-glucosidase activity was found to have no effect on auxin- or acid-promoted growth. It is concluded that neither beta-galactosidase nor beta-glucosidase plays an important role in short term growth promotion by auxin or acid. The data do not rule out the possibility that some other cell wall glycosidase is involved in auxin or acid action.

Journal Article↗

PubMed1988

Construction of a Stable alpha-Galactosidase-Producing Baker's Yeast Strain.

Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by Saccharomyces strains requires the secretion of alpha-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel. In this study we integrated the yeast MEL1 gene, which codes for alpha-galactosidase, into a commercial mel baker's yeast strain. The Mel phenotype of the new strain was stable. The MEL1 gene was expressed when the new Mel baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The alpha-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produced considerably more alpha-galactosidase than did a wild-type Mel strain and may prove useful for commercial production of alpha-galactosidase.

Journal Article↗

PubMed1995

Ligand-independent activation of tyrosine kinase in fibroblast growth factor receptor 1 by fusion with beta-galactosidase.

To examine the biological role of fibroblast growth factor receptor 1 (FGFR1) oligomerization for its signal transduction, we construct an expression vector encoding a FGFR1-beta-galactosidase fusion protein. This vector is designed to fuse the 3'-portion of FGFR1 to beta-galactosidase. Transfection of this vector into FGFR-negative rat L6 myoblast cells results in ligand-independent inhibition of differentiation into myocytes, suggesting that FGFR1 within this fusion protein is constitutively activated. This can be confirmed by demonstrating that this fusion protein exhibits the tyrosine kinase activity and phospholipase C gamma 1 is tyrosine-phosphorylated even in the absence of ligand stimuli. Since the transfected cells also exhibit the enzyme activity of beta-galactosidase which is known to be active only in a tetramer form, this constitutive activation can be elicited by tetramerization of FGFR1. Furthermore, deletion of a region corresponding to C terminal 10 amino acids important for tetramerization of beta-galactosidase from this expression vector abolishes the constitutively active nature of FGFR1 with simultaneous loss of beta-galactosidase activity. Transfection of non-deleted expression vector into NIH3T3 cells results in acquisition of focus-forming activity while a deleted form of expression vector fails to show this activity even in the presence of basic FGF. These results would suggest that tetramerization of FGFR1 can produce a constitutively active form responsible for transformation of NIH3T3 cells.

3T3 Cells↗

PubMed1980

Beta-galactosidase deficiency: studies of two patients with prolonged survival.

Two adults with beta-galactosidase deficiency were studied. Differences in a number of beta-galactosidase parameters (pH optima, heat denaturation, NaCl kinetics) were noted between the patients. Differences were also noted in beta-galactosidase electrophoretic mobilities and urinary oligosaccharides; however, there was no complementation in cell fusion studies. It is suggested that these two patients have different primary mutations at the beta-galactosidase locus which are probably structural in nature.

Adult↗

PubMed1983

Morquio B syndrome: a primary defect in beta-galactosidase.

Fibroblasts from patients with Morquio B syndrome contain normal numbers of beta-galactosidase molecules with normal turnover but strongly reduced activity per enzyme molecule. Various substrate affinities are abnormal: the Km for methylum belliferyl (MU)-beta-galactoside is 4-10-fold elevated and affinity for keratan sulphate and oligosaccharides, isolated from Morquio B urine, was not detectable. In contrast, these substrate affinities are normal for beta-galactosidase in adult type GM1-gangliosidosis fibroblasts. Cell hybridization studies demonstrate that Morquio B syndrome and infantile and adult type GM1-gangliosidosis belong to the same complementation group. From these results we conclude that Morquio B syndrome is caused by a mutation in the structural gene for beta-galactosidase, which is allelic to the mutations in infantile and adult type GM1-gangliosidosis. Urinary excretion of keratan sulphate and oligosaccharides is abnormal in Morquio B syndrome but normal in adult type GM1-gangliosidosis. The catalytic properties of beta-galactosidase in Morquio B syndrome and GM1-gangliosidosis provide a possible explanation for the distinct clinical manifestations in these disorders.

Fibroblasts↗

PubMed1988

Inherited lysosomal storage disease associated with deficiencies of beta-galactosidase and alpha-neuraminidase in sheep.

Histopathologic, ultrastructural and Golgi impregnation studies disclosed lesions characteristic of a neuronal lysosomal storage disease in related sheep with onset of neurologic signs at 4-6 months. Biochemical and enzymatic evaluation disclosed storage of GM1 ganglioside, asialo-GM1, and neutral long chain oligosaccharides in brain, urinary excretion of neutral long chain oligosaccharides, and deficiencies of lysosomal beta-galactosidase and alpha-neuraminidase. Retrospective and limited prospective genetic studies suggested autosomal recessive inheritance. A gene-dosage effect on beta-galactosidase levels was documented in fibroblasts from putative heterozygous sheep. Fibroblasts from affected sheep did not have increased beta-galactosidase activity after incubation with the protease inhibitor, leupeptin. In some aspects this disease is similar to GM1 gangliosidosis, but is unique in that a genetic defect in lysosomal beta-galactosidase may cause the deficiency of lysosomal alpha-neuraminidase.

Animals↗

PubMed1980

Immobilization of beta-galactosidase and other enzymes onto p-amino-carbanilated cellulose derivatives.

beta-Galactosidase and other enzymes were immobilized on p-amino-carbanilated derivatives of cellulose and methylol cellulose using the diazo method and through glutaraldehyde. The optimum conditions for coupling cellulose tri-(p-amino-carbanilate) (CTAC) to beta-galactosidase were established. The diazo coupling method with CTAC gave greater activity than with glutaraldehyde when coupled to beta-galactosidase (Escherichia coli). The stability of the CTAC-beta--galactosidase system was examined. The disubstituted p-amino-carbanilate derivative (CDAC) gave a lower activity, whereas the methylol analog (MCTAC) gave slightly greater activity. The CTAC was also used to immobilize glucose oxidase, trypsin, pepsin, and papain.

Amines↗

PubMed1986

Detection of acid-beta-galactosidase activity in viable human fibroblasts by flow cytometry.

The fluorogenic substrate fluorescein-di-beta-D-galactopyranoside was used to detect acid beta-galactosidase in intact cultured human fibroblasts. The accumulation of intracellular fluorescein, as measured by flow cytophotometry was linear with the incubation time in three control strains. The two fibroblast strains from patients with acid beta-galactosidase deficiency did not show an accumulation of intracellular fluorescence. Within one control cell population there was a positive correlation between the amount of accumulated intracellular fluorescein fluorescence and the specific acid beta-galactosidase activity as measured biochemically on sorted cells from different zones of the fluorescence distribution. No correlation was found between the specific acid beta-galactosidase activity and the fluorescein fluorescence of three different control cell strains.

Cells, Cultured↗

PubMed1985

Constraints in T-B cooperation related to epitope topology on E. coli beta-galactosidase. I. The fine specificity of T cells dictates the fine specificity of antibodies directed to conformation-dependent determinants.

Experiments to test the relationship between the epitopes on a protein antigen recognized by T and B cells in their collaboration to produce antibody cannot rely solely on hapten-carrier models. In the present work we used E. coli beta-galactosidase, a molecule whose tertiary and quaternary epitopes have been well characterized, as the model antigen. T helper cells were raised by stimulating mice with the intact or the denatured molecule or with any of several beta-galactosidase cyanogen bromide peptides. In a series of in vitro helper T cell assays we confronted the various T populations with B cells preimmunized with the native antigen, and we tested their capacity to help production of (a) binding antibodies and (b) antibodies directed to single conformational epitopes, characterized by their capacity to protect the enzyme from heat denaturation or to activate defective beta-galactosidase. According to our results, (a) equivalent T cell help can be provided by T helper cells primed with native or denatured antigen, even for the production of "conformational" antibodies; (b) one of the peptides (CB-18) is most efficient in raising help for binding antibodies; and (c) two peptides (CB-20 and CB-21) rank highest in priming T helper cells for the eventual production of protecting and activating antibodies, respectively. Thus, not every beta-galactosidase-specific T helper cell is useful in providing help to B cells specific for any particular epitope on the molecule, but rather preferential pairings exist, possibly governed by a proximity rule.

Animals↗

PubMed1980

The specificity of beta-galactosidase in the degradation of gangliosides.

Available evidence indicates that a least two genetically distinct acidic lysosomal beta-galactosidases are present in mammalian tissues. One of them, galactosylceramidase, is primarily responsible for degradation of galactosylceramide, galactosylsphingosine, and monogalactosyl-diglyceride, while the other, GM1-ganglioside beta-galactosidase, degrades GM1-ganglioside and asialo GM1-ganglioside. Lactosylceramide can be hydrolyzed by either of the two enzymes. These substrate specificities of the two beta-galactosidases can adequately explain the known findings in the two genetic beta-galactosidase deficiency diseases. The possibilities of the specific lactosylceramidase have not yet received the necessary independent confirmation.

Brain↗

PubMed1982

beta-Galactosidase alpha-complementation. A model of protein-protein interaction.

Studies on beta-galactosidase alpha-complementation are reviewed. The isolation and structure of two beta-galactosidase fragments that form an enzymically active complex are described. One of these is a cyanogen bromide peptide from whole beta-galactosidase; the other is a dimeric protein from a lacZ deletion mutant of Escherichia coli. The mechanism most likely involves an initial binding of two cyanogen bromide peptides to the dimer, followed by formation of a tetramer, and finally a slow conformational change of the complex to a native-like enzyme. The overall reaction is essentially irreversible. A region of the polypeptide chain involved in dimer-dimer contact must be supplied by the cyanogen bromide peptide. alpha-Complemented enzyme contains overlapping sequences. Proteolytic experiments were carried out to determine the origin of the functionally important segment. The effect on alpha-complementation of amino acid substitutions at four positions in the polypeptide chain was investigated. The implications of these results for beta-galactosidase structure and for proteins in general are discussed.

Amino Acid Sequence↗

PubMed1979

Assignment of structural beta-galactosidase loci to human chromosomes 3 and 22.

Hybrid cell lines isolated after fusions between Chinese hamster E36 cells and normal human white blood cells were analyzed for human beta-galactosidase isoenzymes and for human chromosomes, especially 3, 12, and 22, the candidates for bearing a beta-galactosidase locus. Results of neuraminidase treatment of the cell lysates and immunological studies showed that in man two structural beta-galactosidase loci are present and can be assigned to chromosomes 3 and 22. No correlation was found between the expression of human beta-galactosidase and the presence of human chromosome 12.

Animals↗

PubMed1984

Expression of heat shock-beta-galactosidase hybrid genes in cultured Drosophila cells.

Derivatives of Drosophila 70,000 dalton heat shock protein (hsp70) genes were constructed in which all of the hsp70 coding sequence but for the first seven codons had been substituted by a DNA segment coding for E. coli beta-galactosidase. The constructs were capable of directing the synthesis of active beta-galactosidase in COS1 (SV40 transformed African Green Monkey Kidney) cells. The hybrid genes were then used to develop a procedure permitting the introduction of genes and their transient expression in cultured cells of Drosophila melanogaster. Introduction of hybrid genes was achieved by DEAE-dextran-mediated transfection. Substantial gene activity was observed in heat-treated cells only 4 h, maximal activity 24 h after transfection. Various parameters of the transfection/transient expression system including the effects of different 3'nontranslated sequences on hybrid gene expression were investigated in an attempt to provide a useful procedure for studies of the expression of other genes in D. melanogaster cells. To show that promoters which are weaker than that of the hsp70 gene direct the synthesis of easily measurable amounts of beta-galactosidase in D. melanogaster cells, the expression of a hsp84-beta-galactosidase hybrid gene was also examined. Expression of the hsp70 hybrid gene occurs during heat shock, at temperatures at which other proteins are not made, and decreases sharply after heat treatment. The expression of the transfected gene therefore closely follows that of the endogenous hsp70 genes. This result suggests that a short hsp70 gene segment consisting of 195 base pairs of upstream sequence and a complete RNA leader region contain all the information required for the induced synthesis of proteins during heat shock.

Animals↗

PubMed1987

Origin of the enhanced activity of lysosomal beta-galactosidase in serum and skin in progressive systemic sclerosis.

In 14 patients with progressive systemic sclerosis (PSS) the activities of acid lysosomal glycosidases (alpha-, beta-galactosidase, beta-glucosidase, beta-glucuronidase, and beta-N-acetyl-glucosaminidase) were determined fluorometrically in serum, leukocytes, and skin tissue. The beta-galactosidase was the only enzyme which exhibited a significantly elevated activity in PSS serum and skin but not leukocytes, as compared to the control. The activity patterns of the studied glycosidases in serum were similar to those found in skin, but differ from the distribution of glycosidase activities in leukocytes. In cultured dermal fibroblasts derived from PSS patients, an elevated intracellular activity of beta-galactosidase was detected. These results suggest that the increased beta-galactosidase activity in the serum originates from the skin fibroblasts.

Adult↗