Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The immune response to beta-galactosidase (beta-D-galactoside galactohydrolase; EC 3.2.1.23)is characterized by a wave of early help followed by a wave of suppression to a subsequent in vitro challenge with galactosidase-fluorescein. A cyanogen bromide peptide of beta-galactosidase, CB2, mimics the suppression seen with the enzyme. It is time dependent, carrier specific, and anti-theta sensitive; however, this suppression is not preceded by a wave of help. It is possible that CB2 cannot stimulate helpers, and is only able to activate suppressor cells. These data indicate that one small region of an antigen, capable of activating suppressors, can nullify the positive effect induced in helper T cells reactive with other epitopes on beta-galactosidase. Key determinants on macromolecules may in this way be influential in regulating the immune response to the entire antigen molecule.
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PMID:Key antigenic determinants in regulation of the immune response. 7 36

The Fluoro Ultra Micro Enzyme Linked Immuno Assay (FUMELIA) allows one routinely and quantitatively to measure a few thousand antigenic determinants on single cells. Highly purified Escherichia coli beta-galactosidase has been coupled to specific antibodies. By use of the Parafilm microcuvette techniuqe, the activity of the antibody-conjugated beta-galactosidase is assayed with a conventional spectrophotofluorometer. Attempts were undertaken to sensitize FUMELIA even further, so as to be able to detect a very few antigenic sites. It seems that even in its present state of development FUMELIA is more sensitive for the quantitation of cell-associated antigens than are techniques in which radiolabeled reagents are used. The potential of FUMELIA is illustrated by the quantitative measurement of membrane-bound immunoglobulins on single lymphocytes. It could be shown that T-cells as well as C-cells can synthesize Ig antigenic determinants. Thus it seems likely that T-cell receptors will, after all, be found to be immunoglobulins.
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PMID:Quantitative ultramicro-scale immunoenzymic method for measuring Ig antigenic determinants in single cells. 7 53

A cloned DNA transcript of ovalbumin mRNA was cut a few nucleotides away from the initiator codon, and fused in phase to the beginning of the Escherichia coli beta-galactosidase gene. The hybrid gene has been cloned in E. coli where it produces large amounts of an ovalbumin-like protein.
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PMID:Synthesis of an ovalbumin-like protein by Escherichia coli K12 harbouring a recombinant plasmid. 8 Jul 51

The BALB/c secondary response against the beta-galactosidase (beta-gal) enzyme of E. Coli was analyzed at the precursor cell level by using the splenic focus technique. Our results indicate that in immunized mice, one out of 18 000 B cells is able to recognize beta-gal. Among the families of anti-beta-gal monoclonal antibodies, a subset of specific antibodies was detected which is capable of protecting the enzyme from heat denaturation. The frequency of clones making protecting antibodies is 1 out of 90 000 and appears to be fairly constant among different individual mice. Further, the degree of heterogeneity of protecting antibodies analyzed in one individual is very high (250-fold difference in affinity) but comparable to other secondary repertoires. Specific frequencies are compared with previous findings relative to secondary responses against artificial haptens. It is suggested that a different type of recognition exists between protein determinants and artificial haptens. In addition, the relatively high proportion of clones making antibodies of the protecting type suggests that only a small proportion of antigenic sites on the beta-gal is actually able to stimulate an immune response.
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PMID:Immune response against the beta-galactosidase enzyme of E. coli at precursor cell level. I. Analysis of the secondary repertoire in BALB/c mice. 8 79

The residual liver acid beta-galactosidase (beta-gal) activity from a case of feline GM1 gangliosidosis was partially purified and characterized with respect to its pH optimum, kinetic properties, thermostability, isoelectric point, molecular weight, and antigenicity. In comparison to the normal enzyme, the mutant enzyme had the same pH optima for the three substrates tested, a reduced Km for 4-methylumbelliferyl-beta-gal, elevated Km's for GM1 and asialofetuin (ASF), and increased thermolability. In addition, the mutant beta-gal had a higher isoelectric point, a reduced molecular weight, and appeared to be antigenically different from normal. The results suggest that the mutation in the Birmingham GM1 cat is structural and that the residual enzyme activity is a structurally altered acid beta-gal. The apparent lack of antigenic identity between the mutant and normal enzymes, in contrast to the situation in many human GM1 patients, is most unusual.
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PMID:Feline GM1 gangliosidosis: characterization of the residual liver acid beta-galactosidase. 8 95

alpha Complementation in beta-galactosidase is the restoration of enzyme activity by addition of the alpha donor CNBr2, from amino acid residues 3--92 of the polypeptide, to inactive M15 protein from the lacZ deletion mutant strain M15. M15 protein lacks residues 11--41 and is a dimer; the active complex, like native beta-galactosidase, is tetrameric [Langley, K. E., & Zabin, I. (1976) Biochemistry 15, 4866--4875]. A dimer--dimer binding region in beta-galactosidase has been identified by proteolytic and immunologic studies of alpha-complementation. Proteolytic experiments were carried out with trypsin. Treatment of native beta-galactosidase with trypsin, followed by reaction of the mixture with cyanogen bromide, yields intact CNBr2 as measured by its ability to complement M15 protein. Active CNBr2 is not obtained when urea-denatured beta-galactosidase is treated in the same way. Therefore the segment corresponding to CNBr2 is apparently buried within the folded protein. Immunologic experiments were carried out with antibodies against CNBr2, tryptic peptide T8 (residues 60--140), and CNBr3 (residues 93--187). Anti-CNBr2 and anti-T8 bind to M15 protein but not to beta-galactosidase, indicating that this area is exposed in the dimer. Anti CNBr2, but not anti-T8 or anti-CNBr3, inhibits the formation of alpha-complemented enzyme. These results indicate that an early part of the sequence, within the segment corresponding to CNBr2, is involved in dimer--dimer interaction.
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PMID:A dimer--dimer binding region in beta-galactosidase. 8 82

Synthetic genes for human insulin A and B chains were cloned separately in plasmid pBR322. The cloned synthetic genes were then fused to an Escherichia coli beta-galactosidase gene to provide efficient transcription and translation and a stable precursor protein. The insulin peptides were cleaved from beta-galactosidase, detected by radioimmunoassay, and purified. Complete purification of the A chain and partial purification of the B chain were achieved. These products were mixed, reduced, and reoxidized. The presence of insulin was detected by radioimmunoassay.
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PMID:Expression in Escherichia coli of chemically synthesized genes for human insulin. 8

Histochemical staining for enzymes is usually performed on frozen sections. This report lists the longer incubation times required to demonstrate esterase, acid phosphatase, beta-galactosidase, and cytochrome oxidase in plastic embedded and ruotine paraffin embedded tissues. The sections embedded in plastic, i.e. water soluble methacrylate (Polyscience's JB-4) and cut at 2 micrometers, were far superior to frozen sections and paraffin embedded sections both in tissue detail and in the localization of the histochemical reaction product.
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PMID:Histochemical demonstration of enzyme activities in plastic and paraffin embedded tissue sections. 9 Apr 11

A case of adult type mucolipidosis with beta-galactosidase and sialidase deficiency is described. This patient, a woman aged 20, had mental retardation, macular cherry-red spots, corneal clouding, gargoyle-like face, cerebellar ataxia, myoclonus and convulsions beginning at the age of 14. Bony deformities, vacuoles in the peripheral lymphocyte and foamy cells in the bone marrow were also noted. Biopsy study of the sural nerve and vermiform appendix disclosed many vacuoles in almost every kind of cells, although the accumulated substance in these vacuoles could not be characterized histochemically or ultrastructurally. Deficient leukocyte beta-galactosidase and sialidase were confirmed. There was increased urinary sialoglycopeptide and increased siliac acid and hexosamine in the glycoprotein of lymphocytes. Leukocytes sialidase activites of the parents were 30 to 50% of the control values. These results suggest a genetic defect of sialidase.
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PMID:Adult type mucolipidosis with beta-galactosidase and sialidase deficiency. Histological and biochemical studies. 9 67

Fruiting body formation in the bacterium Myxococcus xanthus consists of a temporal sequence of cellular aggregation and sporulation. During the period of cellular aggregation, a major new development-specific protein that has lectin-like activity is synthesized. This protein, called myxobacterial hemagglutinin (MBHA), was able to agglutinate sheep or guinea pig erythrocytes but not horse, ox, chicken, or human erythrocytes. MBHA was undetectable in extracts of vegetative cells, cells starved in liquid buffer, or in glycerol-induced cells. However, cells starved on a fruiting medium produced large amounts of MBHA (about 5% of protein synthesis), starting at about 6-8 hr of development. The protein accumulated in the soluble fraction of cells, reaching a peak of 1-2% of total protein at about the time when aggregation was completed. At later times the amount of MBHA present in the soluble fraction declined although synthesis continued. The hemagglutinating activity of MBHA could not be inhibited with simple sugars or aminosugars but could be inhibited with fetuin, a fetal calf serum glycoprotein. The O-glycosidically linked trisaccharide glycopeptide of fetuin was shown to be inhibitory by itself. The penultimate galactose of this glycopeptide was directly implicated in the inhibitory activity, because the inhibition by asialofetuin was reduced to 1/60th by periodate oxidation and to 1/15th after beta-galactosidase treatment. MBHA is an abundant biochemical marker of development in M. xanthus. The fact that it is a lectin suggests that it may play a role in cell-cell recognition or agglutination.
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PMID:Myxobacterial hemagglutinin: a development-specific lectin of Myxococcus xanthus. 9 78


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