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At least 19 recordsLinked to original sources
PubMed1991

Use of inactive beta-D-galactosidase for elimination of interference by anti-beta-D-galactosidase antibodies in immune complex transfer enzyme immunoassay for anti-thyroglobulin IgG in serum using beta-D-galactosidase from Escherichia coli as label.

A novel enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG using beta-D-galactosidase from Escherichia coli as label was reported previously. This immunoassay was highly sensitive in demonstrating anti-thyroglobulin IgG not only in all patients with Graves' disease and chronic thyroiditis but also in a large proportion of healthy subjects. However, the detection of anti-thyroglobulin IgG at low levels in some serum samples was difficult, probably due to the presence of anti-beta-D-galactosidase antibodies. In the present study, the use of inactive beta-D-galactosidase was tested for elimination of interference by anti-beta-D-galactosidase antibodies. Preincubation of serum samples with excess of inactive beta-D-galactosidase resulted in sufficiently low backgrounds to detect low levels of anti-thyroglobulin IgG with little effect on the dose-response of anti-thyroglobulin IgG. As a result, it was revealed that anti-thyroglobulin IgG was present in almost all healthy subjects as well as all patients with Graves' disease and chronic thyroiditis.

Adult↗
PubMed2001

Pore network modelling of affinity chromatography: determination of the dynamic profiles of the pore diffusivity of beta-galactosidase and its effect on column performance as the loading of beta-galactosidase onto anti-beta-galactosidase varies with time.

A three-dimensional pore network model for diffusion in porous adsorbent particles was employed in a dynamic adsorption model that simulates the adsorption of a solute in porous particles packed in a chromatographic column. The solution of the combined model yielded the dynamic profiles of the pore diffusion coefficient of beta-galactosidase along the radius of porous adsorbent particles and along the length of the column as the loading of beta-galactosidase onto anti-beta-galactosidase immobilized on the surface of the pores of the particles occurred, and, the dynamic adsorptive capacity of the chromatographic column as a function of the design and operational parameters of the chromatographic system. It was found that for a given column length the dynamic profiles of the pore diffusion coefficient were influenced by (a) the superficial fluid velocity in the column, (b) the diameter of the adsorbent particles, and (c) the pore connectivity of the porous structure of the adsorbent particles. The effect of the magnitude of the pore connectivity on the dynamic profiles of the pore diffusion coefficient of beta-galactosidase increased as the diameter of the adsorbent particles and the superficial fluid velocity in the column increased. The dynamic adsorptive capacity of the column increased as (i) the particle diameter and the superficial fluid velocity in the column decreased, and (ii) the column length and the pore connectivity increased. In preparative affinity chromatography, it is desirable to obtain high throughputs within acceptable pressure gradients, and this may require the employment of larger diameter adsorbent particles. In such a case, longer column lengths satisfying acceptable pressure gradients with adsorbent particles having higher pore connectivity values could provide high dynamic adsorptive capacities. An alternative chromatographic system could be comprised of a long column packed with large particles which have fractal pores (fractal particles) that have high pore connectivities and which allow high intraparticle diffusional and convective flow mass transfer rates providing high throughputs and high dynamic adsorptive capacities. If large scale monoliths could be made to be reproducible and operationally stable, they could also offer an alternative mode of operation that could provide high throughputs and high dynamic adsorptive capacities.

Adsorption↗
PubMed1977

Construction, isolation and implications of repressor-galactosidase - beta-galactosidase hybrid molecules.

Escherichia coli heterogenotes, which produce hybrid molecules between the chimaeric protein repressor-galactosidase and the enzyme beta-galactosidase, were constructed. Repressor-galactosidase in which fully active lac repressor is covalently linked to active beta-galactosidase, is an aggregate with a core structure of four beta-galactosidase parts and two peripheral lac repressor dimers. The lac repressor dimers, which are separated by tetrameric beta-galactosidase, retain all the biological activities of tetrameric lac repressor. Substitution of repressor-galactosidase subunits with beta-galactosidase subunits leads to hybrid molecules with y beta-galactosidase subunits aggregated with (4-y) repressor-galactosidase subunits (where y = 1, 2 or 3). A 2:2 hybrid, i.e. a tetrameric beta-galactosidase core with one lac repressor dimer grafted to it, binds at least 100 times less strongly to 32P-labelled lambdaplac DNA than pure lac repressor or repressor-galactosidase. The data suggest a model in which lac repressor binds with two subunits to lac operator and with the other two subunits elsewhere on the DNA, possibly on sequences like the lac operator.

Bacterial Proteins↗
PubMed1981

Turnover of beta-galactosidase in fibroblasts from patients with genetically different types of beta-galactosidase deficiency.

The turnover of lysosomal beta-galactosidase was studied in fibroblast cultures from patients with Gm1-gangliosidosis and combined beta-galactosidase and neuraminidase deficiency, which had 5-10% residual beta-galactosidase activity. beta-Galactosidase was specifically inactivated with the suicide substrate beta-D-galactopyranosylmethyl-p-nitro-phenyltriazene (beta-Gal-MNT) and from the subsequent restoration of enzyme activity in cell cultures turnover times were calculated. By using [3H]beta-Gal-MNT, the hydrolytic activity per molecule of beta-galactosidase was determined. 3H-labelled beta-D-galactopyranosylmethylamine, the precursor of [3H]beta-gal-MNT, was obtained by Raney-nickel-catalysed exchange with 3H2O. The rate of synthesis of beta-galactosidase in normal and all mutant cells tested was found to be 0.4-0.5 pmol/day per mg of cellular protein. The GM1-gangliosidosis cells tested contain the normal amount of 0.5 pmol of beta-galactosidase/mg of protein with a normal turnover time of about 10 days, but only 10% of beta-galactosidase activity per enzyme molecule. Cells with combined beta-galactosidase and neuraminidase deficiency contain only 0.3 pmol of beta-galactosidase/mg of protein with a decreased turnover time of 1 day and normal hydrolytic properties (200 nmol of 4-methylumbelliferyl galactoside/h pmol of beta-galactosidase).

Binding Sites↗
PubMed1989

Insulin-like growth factor-II (IGF-II) inhibits both the cellular uptake of beta-galactosidase and the binding of beta-galactosidase to purified IGF-II/mannose 6-phosphate receptor.

The insulin-like growth factor-II/mannose 6-phosphate receptor which targets acid hydrolases to lysosomes, has two different binding sites, one for the mannose 6-phosphate (Man-6-P) recognition marker on lysosomal enzymes and the other for insulin-like growth factor-II (IGF-II). We have asked whether IGF-II can regulate the cellular uptake of the lysosomal enzyme 125I-beta-galactosidase by modulating the binding of 125I-beta-galactosidase to the IGF-II/Man-6-P receptor. We first isolated high affinity 125I-beta-galactosidase by affinity chromatography on an IGF-II/Man-6-P receptor-Sepharose column. Specific uptake (mannose 6-phosphate-inhibitable) of 125I-beta-galactosidase in BRL 3A2 rat liver cells and in rat C6 glial cells was 3.7-4.8 and 4.0-8.0% of added tracer, respectively. The cell-associated 125I-beta-galactosidase in the uptake experiments largely represented internalized radioligand as measured by acid or mannose 6-phosphate washing. The uptake of 125I-beta-galactosidase was inhibited by an antiserum (No. 3637) specific for the IGF-II/Man-6-P receptor. Low concentrations of IGF-II also inhibited the uptake of 125I-beta-galactosidase. Maximal concentrations of IGF-II inhibited uptake by 73 +/- 8% (mean +/- S.D.) in C6 cells and by 77 +/- 6% in BRL 3A2 cells compared to the level of inhibition by mannose 6-phosphate. The relative potency of IGF-II, IGF-I, and insulin (IGF-II much greater than IGF-I; insulin, inactive) were characteristic of the relative affinities of the ligands for the IGF-II/Man-6-P receptor. IGF-II also partially inhibited the binding of 125I-beta-galactosidase to C6 and BRL 3A2 cells at 4 degrees C and inhibited the binding to highly purified IGF-II/Man-6-P receptor by 58 +/- 14%. We conclude that IGF-II inhibits the cellular uptake of 125I-beta-galactosidase and that this inhibition is partly explained by the ability of IGF-II to inhibit binding of 125I-beta-galactosidase to the IGF-II/Man-6-P receptor.

Animals↗
PubMed1985

The chromosomal localization of human beta-galactosidase revisited: a locus for beta-galactosidase on human chromosome 3 and for its protective protein on human chromosome 22.

A series of man-Chinese hamster and man-mouse somatic cell hybrids was investigated to study the localization of the genes coding for the human lysosomal enzyme beta-galactosidase (EC 3.2.1.23) and for its protective protein. Using a monoclonal antibody, raised against human placental beta-galactosidase, it was observed that the structural locus for the beta-galactosidase polypeptide is located on chromosome 3. The nature of the involvement of chromosome 22 in the expression of human beta-galactosidase was elucidated by metabolic labelling of the hybrids with radioactive amino acids, immunoprecipitation with monoclonal and polyclonal antibodies against beta-galactosidase, followed by analysis via gel electrophoresis and fluorography. The data show that the presence of chromosome 22 coincides with the presence of a 32 kd protein. This polypeptide, the "protective protein" was previously shown to be intimately associated with human beta-galactosidase. In addition, the protective protein was found to be essential for the in vivo stability of beta-galactosidase by aggregating beta-galactosidase monomers into high molecular weight multimers. Both chromosome 3 and 22 are therefore necessary to obtain normal levels of beta-galactosidase activity in human cells.

Animals↗
PubMed1990

Glycosidases of Ehrlich ascites tumor cells and ascitic fluid--purification and substrate specificity of alpha-N-acetylgalactosaminidase and alpha-galactosidase: comparison with coffee bean alpha-galactosidase.

Ehrlich ascites tumor cells and ascitic fluid were assayed for glycosidase activity. alpha-Galactosidase and beta-galactosidase, alpha- and beta-mannosidase, alpha-N-acetylgalactosaminidase, and beta-N-acetylglucosaminidase activities were detected using p-nitrophenyl glycosides as substrates. alpha-Galactosidase and alpha-N-acetylgalactosaminidase were isolated from Ehrlich ascites tumor cells on epsilon-aminocaproylgalactosylamine-Sepharose. alpha-Galactosidase was purified 160,000-fold and was free of other glycosidase activities. alpha-N-Acetylgalactosaminidase was also purified 160,000-fold but exhibited a weak alpha-galactosidase activity which appears to be inherent in this enzyme. Substrate specificity of the alpha-galactosidase was investigated with 12 substrates and compared with that of the corresponding coffee bean enzyme. The pH optimum of the Ehrlich cell alpha-galactosidase centered near 4.5, irrespective of substrate, whereas the pH optimum of the coffee bean enzyme for PNP-alpha-Gal was 6.0, which is 1.5 pH units higher than that for other substrates of the coffee bean enzyme. The reverse was found for alpha-N-acetylgalactosaminidase: the pH optimum for the hydrolysis of PNP-alpha-GalNAc was 3.6, lower than the pH 4.5 required for the hydrolysis of GalNAc alpha 1,3Gal. Coffee bean alpha-galactosidase showed a relatively broad substrate specificity, suggesting that it is suited for cleaving many kinds of terminal alpha-galactosyl linkages. On the other hand, the substrate specificity of Ehrlich alpha-galactosidase appears to be quite narrow. This enzyme was highly active toward the terminal alpha-galactosyl linkages of Ehrlich glycoproteins and laminin, both of which possess Gal alpha 1, 3Gal beta 1,4GlcNAc beta-trisaccharide sequences. The alpha-N-acetylgalactosaminidase was found to be active toward the blood group type A disaccharide, and trisaccharide, and glycoproteins with type A-active carbohydrate chains.

Animals↗
PubMed1995

Human lysosomal beta-galactosidase-cathepsin A complex: definition of the beta-galactosidase-binding interface on cathepsin A.

Human lysosomal beta-galactosidase is organized as a 680-kDa complex with cathepsin A (also named carboxypeptidase L and protective protein), which is necessary to protect beta-galactosidase from intralysosomal proteolysis. To understand the molecular mechanism of beta-galactosidase protection by cathepsin A, we defined the structural organization of their complex including the beta-galactosidase-binding interface on cathepsin A. Radiation inactivation analysis suggested the existence of a 168-kDa structural subunit of the complex containing both beta-galactosidase and cathepsin A. Chemical cross-linking of the complex confirmed the existence of this subunit and showed that it is composed of one cathepsin A dimer and one beta-galactosidase monomer. The modeling of the cathepsin A dimer tertiary structure based on atomic coordinates of a wheat carboxypeptidase suggested a putative beta-galactosidase-binding cavity formed by the association of two cathepsin A monomers. According to this model two exposed loops of cathepsin A bordering the cavity were chosen as part of a putative beta-galactosidase-binding interface. Synthetic peptides corresponding to these loops were found both to dissociate the complex and to inhibit its in vitro reconstitution from purified cathepsin A and beta-galactosidase. The defined location of the GAL monomer in the complex with 35% of its surface covered by the CathA dimer may explain the stabilizing effect of CathA on GAL in lysosome.

Amino Acid Sequence↗
PubMed1978

Acid glycohydrolase in Chinese hamster with spontaneous diabetes. I. Depressed levels of renal alpha-galactosidase and beta-galactosidase.

The activites of alpha-and Beta-galactosidases (alpha-D-galactoside galactohydrolase, EC 3.2.1.22; beta-D-galactoside galactohydrolase, EC 3.2.1.23) were significantly lower in the kidneys of diabetic XA line than those in the nondiabetic M line Chinese hamsters. The depression of these enzymes was found only in the kidney but not in liver, spleen, hind leg muscle, cheek pouch or spinal cord. In young XA animals before onset of glycosuria, renal alpha-galactosidase level was similar to that in age-matched M animals; whereas, their renal beta-galactosidase activity was about 90% of those in the M animals. Partial purification and separation of these enzymes were achieved by chromatography on DEAE-Sepharose CL-6B columns. beta-galactosidase was separated into two isozymes and depression of activity in the XA kidneys was evident in both. alpha-galactosidase was recovered in a single peak. The pH optima of these enzymes from XA and M animals were identical. With p-nitrophenyl glycosides as substrates, the Michaelis constants of these enzymes were also the same of XA and M animals. Molecular weight estimation by gel filtration on Sepharose 6B yielded similar results between M and XA samples: 2.4-10(5) for alpha-galactosidase and 1.6.10(5) and 1.9.10(5) for beta-galactosidase isozymes. The data suggest that the diabetic animals had lower concentrations of alpha-and beta-galactosidase in their kidneys, probably as a consequence of hyperglycemia.

Animals↗
PubMed1981

Genetic regulation: yeast mutants constitutive for beta-galactosidase activity have an increased level of beta-galactosidase messenger ribonucleic acid.

Mutants of Kluyveromyces lactis with elevated uninduced levels of beta-galactosidase (EC 32.1.2.3) activity, constitutive mutants (lac10c), were isolated and characterized to determine the basis for their constitutiveness. These lesions are not operator-type regulatory mutants because they are not closely linked to the beta-galactosidase structural gene. In a constitutive strain having a 7-fold increase in beta-galactosidase activity, the concentration of beta-galactosidase messenger ribonucleic acid (mRNA) was 8- to 10-fold higher than uninduced wild type. The half-life of beta-galactosidase mRNA was the same in the mutant strain (t1/2 = 4.5 +/- 0.2 min) as in uninduced wild-type cells (t1/2 = 4.8 +/- 0.1 min), indicating that the elevated mRNA level in the mutant was not due to a decreased rate of mRNA degradation. Consequently, we hypothesize that the LAC10 product regulates transcription of the beta-galactosidase gene; it probably affects the rate of transcription initiation. Parallel increases in enzyme protein, in constitutive levels of beta-galactosidase activity, and in mRNA further support this position, making translational or posttranslational control by LAC10 unlikely. Several types of data suggest that the LAC10 product functions as a negative regulatory element to prevent transcription. Other data demonstrate that lac10c mutations have pleiotrophic effects, there being constitutive levels not only of beta-galactosidase activity, but also the other lactose-inducible activities of galactokinase (EC 2.7.5.1), galactose-1-phosphate uridyl transferase (EC 2.7.7.10), and lactose transport. It would appear that LAC10 regulates lactose-inducible proteins.

Chromosome Mapping↗
PubMed1989

Alternative splicing of beta-galactosidase mRNA generates the classic lysosomal enzyme and a beta-galactosidase-related protein.

We have isolated two cDNAs encoding human lysosomal beta-galactosidase, the enzyme deficient in GM1-gangliosidosis and Morquio B syndrome, and a beta-galactosidase-related protein. In total RNA from normal fibroblasts a major mRNA of about 2.5 kilobases (kb) is recognized by cDNA probes. A minor transcript of about 2.0 kb is visible only in immunoselected polysomal RNA. A heterogeneous pattern of expression of the 2.5-kb beta-galactosidase transcript is observed in fibroblasts from different GM1-gangliosidosis patients. The nucleotide sequences of the two cDNAs are extensively colinear. However, the short cDNA misses two noncontiguous protein-encoding regions (1 and 2) present in the long cDNA. The exclusion of region 1 in the short molecule introduces a frameshift in its 3'-flanking sequence, which is restored by the exclusion of region 2. These findings imply the existence of two mRNA templates, which are read in a different frame only in the nucleotide stretch between regions 1 and 2. Sequence analysis of genomic exons of the beta-galactosidase gene shows that the short mRNA is generated by alternative splicing. The long and short cDNAs direct the synthesis in COS-1 cells of beta-galactosidase polypeptides of 85 and 68 kDa, respectively. Only the long protein is catalytically active under the assay conditions used, and it is capable of correcting beta-galactosidase activity after endocytosis by GM1-gangliosidosis fibroblasts. The subcellular localization of cDNA-encoded beta-galactosidase and beta-galactosidase-related proteins is different.

Amino Acid Sequence↗
PubMed1993

Selective inactivation of eukaryotic beta-galactosidase in assays for inhibitors of HIV-1 TAT using bacterial beta-galactosidase as a reporter enzyme.

Bacterial beta-galactosidase is one of several reporter enzymes used in studying the transcriptional activity of eukaryotic promoters. Although it is one of the easiest and least expensive enzymes to assay, its use has been limited because of its low sensitivity, which is due in part to endogenous levels of beta-galactosidase in many eukaryotic cells. In this study, we compared the pH and salt requirements, as well as the heat stability, of bacterial and eukaryotic beta-galactosidase in order to identify conditions which would inhibit the beta-galactosidase enzyme endogenous to eukaryotic cells without adversely affecting the activity of either purified bacterial beta-galactosidase or reporter beta-galactosidase produced after transfection of expression vectors into eukaryotic cells. Heat treatment at 50 degrees C for 1 h inactivated the beta-galactosidase activity endogenous to several eukaryotic cell lines by as much as 40-fold without adversely affecting the activity of bacterial beta-galactosidase. This treatment increased the sensitivity of this reporter enzyme and allowed the development of a rapid and quantifiable screening assay for HIV-1 tat inhibitors.

Animals↗
PubMed1998

Characterization of galactosidases from Aspergillus niger: purification of a novel alpha-galactosidase activity.

An enzyme with beta-galactosidase activity and three proteins exhibiting alpha-galactosidase activity were purified from a culture filtrate of Aspergillus niger grown on arabinoxylan. beta-galactosidase, optimally active at pH 4 and 60-65 degrees C, was active against p-nitrophenyl-beta-D-galactopyranoside, lactose, and pectic galactan. It was not able to release galactose from sugar beet pectin or lemon pectin. Its action on pectic galactan was increased by the presence of beta-galactanase. The three forms of alpha-galactosidase activity that showed different molecular masses and pIs were found to have the same mass after deglycosylation with N-glycanase F and to be the same protein based on their N-terminal amino acid sequence data. The purified alpha-galactosidase was shown to be different from alpha-galactosidase A from A. niger. This confirmed the existence of at least two different alpha-galactosidases in A. niger. alpha-Galactosidase, optimally active at pH 4.5 and 50-55 degrees C, was active toward p-nitrophenyl-alpha-D-galactopyranoside, melibiose, raffinose, stachyose, and locust bean gum, on which substrate it exhibited synergism with beta-mannanase.

Amino Acid Sequence↗
PubMed1977

beta-Galactosidase in mucopolysaccharidoses and mucolipidoses. Deficiency of GM1 beta-galactosidase in liver and leukocytes.

beta-Galactosidase activities were studied in livers and leukocytes of mucopolysaccharidoses and mucolipidoses (I-cell disease and adult "beta-galactosidase deficiency" with macular cherry-red spots). Marked deficiency of hepatic 4-methylumbelliferyl (4MU) and GM1 beta-galactosidases was demonstrated in these diseases. Leukocyte GM1 beta-galactosidase was also deficient in mucolipidoses. The parents of the patients with I-cell disease and "beta-galactosidase deficiency" had normal beta-galactosidase activity in plasma and leukocytes, compared to the low enzyme activity in heterozygous carriers of GM1-gangliosidosis. The cause of this enzyme deficiency in these diseases is not clear at present. It seems to be affected seondarily by exgenous factors such as unknown stored materials in the cells. Mucopolysaccharides were not increased in the livers of two cases of I-cell disease and a case of "beta-galactosidase deficiency".

Adolescent↗
PubMed1988

Lysosomal enzyme activities among Chinese: leukocyte alpha-galactosidase and beta-galactosidase.

alpha-Galactosidase and beta-galactosidase activities have been determined in leukocyte preparations from 100 randomly selected Chinese adults. For alpha-galactosidase, two groups with low activities were identified: group I consisted of 3 females having activities below 40% of normal, and group II consisted of 5 males and 1 female with activities about 60% of normal. Family studies suggested that these low alpha-galactosidase activities are genetically determined. Only 1 individual was found to have about 50% of normal beta-galactosidase activity; presumably he is a carrier for beta-galactosidase deficiency (GM1 gangliosidosis).

Adult↗
PubMed1983

Separation of beta-D-galactosidases in rabbit tissues: genetics of neutral beta-D-galactosidase.

Three different types of beta-D-galactosidase (EC 3.2.1.23) could be distinguished in rabbit tissues using electrophoretic procedures. (1) Acid beta-D-galactosidase with a low mobility and maximal activity at pH 3-5 was found in the particulate fraction of various tissue homogenates. This enzyme hydrolyzed 4-methylumbelliferyl-D-galactoside, but no activity against other glycoside substrates could be demonstrated. The enzyme was inhibited by galactono-(1 leads to 4)-lactone. (2) Lactose-hydrolyzing beta-D-galactosidase with an intermediate mobility was found only in juvenile small intestine. Most of the activity was found in the particulate fraction of the cell. The enzyme hydrolyzed several other synthetic glycoside substrates besides lactose. It was most active at pH 5-6 and strongly inhibited by glucono-(1 leads to 5)-lactone but not much affected by galactono-(1 leads to 4)-lactone. (3) Neutral beta-D-galactosidase with a fast mobility and maximal activity at pH 6-8 was found in the soluble fraction of homogenates from liver, kidney, and small intestine. This enzyme also showed a broad substrate specificity; it possessed activity against aryl-beta-D-glucoside, -fucoside, and -galactoside substrates but not against lactose. The enzyme was strongly inhibited by glucono-(1 leads to 5)-lactone and (less) by galactone-(1 leads to 4)-lactone. Neutral beta-D-galactosidase and neutral beta-D-glucosidase (EC 3.2.1.21) are probably identical enzymes in the rabbit. Individual variation, in both electrophoretic mobility and activity, was found for neutral beta-D-galactosidase. Genetic analysis of the electrophoretic variants revealed that two alleles at an autosomal locus are responsible for this variation.

Animals↗
PubMed1988

Molecular cloning of lactose genes in dairy lactic streptococci: the phospho-beta-galactosidase and beta-galactosidase genes and their expression products.

The mesophilic (S. lactis and S. cremoris) and thermophilic (S. thermophilus) dairy lactic streptococci, which are used in industrial dairy fermentations, contain two different lactose hydrolysing enzymes, a phospho-beta-galactosidase and a beta-galactosidase. The central role of these enzymes in the pathways used for lactose transport and degradation is discussed along with their properties and distributions in lactic streptococci. In addition, recent results on the cloning, expression and sequence organization of the genes for the mesophilic phospho-beta-galactosidase and thermophilic beta-galactosidase are reviewed. Original data are presented concerning heterologous gene expression in the study of lactose hydrolysis in lactic streptococci. These include 1) the purification of the S. lactis phospho-beta-galactosidase from an overproducing Escherichia coli, and 2) the expression of the E. coli beta-galactosidase (lacZ) gene in S. lactis employing a lactic streptococcal expression vector.

Cloning, Molecular↗