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 nature of the binding of C. parvum organisms to the surface of glass-adherent mouse peritoneal exudate cells in vitro was studied using pretreatment of the cells with various enzymes and periodate. Trypsin, pronase, beta-galactosidase, phospholipases A, C and D and periodate all caused a decrease in binding to 40-60% of untreated control. Neuraminidase led to a 30% increase in binding. The binding ability returned to normal after 1 h at 37 degrees in culture medium following exposure to all the enzymes apart from pronase, which apparently could not be removed effectively by washing. The presence of EDTA in the medium inhibited recovery from treatment with trypsin and beta-galactosidase; return to normal after exposure to phospholipases A, C and D was slightly affected, whereas recovery from treatment with neuraminidase was unaffected. Cells that had been exposed to periodate did not regain normal binding ability after 1 h in tissue culture medium but the effect could be reversed chemically by treatment with borohydride. The role of different plasma membrane components in non-specific cellular recognition is discussed.
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PMID:Binding of microorganisms to the macrophage plasma membrane; effects of enzymes and periodate. 20 34

The infectivity of a bovine rotavirus was enhanced 140-, 8-, and 3-fold, respectively, by trypsin, protease, and lactase. Ficin, carboxypeptidases A and B, lysozyme, and beta-galactosidase had little effect on the infectivity. Chymotrypsin caused a threefold decrease in the infectivity. Trypsin acts directly on the rotavirus and not on the host cell.
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PMID:Effect of enzymes on rotavirus infectivity. 22 17

Rough and smooth microsomes and Golgi membranes were incubated with UDP[14C]galactose and the incorporation of radioactivity into the lipid extract and into endogenous protein acceptors were measured. Antagonistic pyrophosphatases were inhibited with ATP and interference from beta-galactosidase activity was greatly decreased by carrying out the incubation at pH 7.8. After incubation the particles were centrifuged to remove free oligosaccharide residues. Radioactivity was found in the lipid extract from Golgi membranes but not from rough and smooth microsomes. This radioactivity, however, was not associated with dolichol or retinyl phosphates. The incorporation of radioactivity into proteins of the Golgi fraction was more than double than that of the microsomal fractions. In addition, the transferases in these two types of particles exhibited different properties. Trypsin treatment of intact rough microsomal vesicles, smooth vesicles and Golgi membranes removed about 5, 15 and 50%, respectively, of newly incorporated protein-bound galactose, indicating that the proportion of the newly galactosylated proteins, which are localized at the cytoplasmic surface of the membrane, is lowest in rough microsomes, intermediate in smooth, and highest in Golgi membranes.
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PMID:Incorporation of galactose from UDP-galactose into microsomal and Golgi membranes of rat liver. 69 7

The involvement of glycoconjugates in the insulin-receptor interactions in mouse liver is tested by digestions of membranes with various enzymes. Trypsin decreased the binding of [125I]insulin to liver membranes. After digestion with beta-galactosidase no ""high affinity'' receptor sites could be detected. The effects observed with plant lectins confirm the involvement of galactoconjugates in the insulin binding process. Sophora japonica and Ricinus communis lectins (with galactose specificity) and concanavalin A largely inhibit the binding process of insulin and those effects concern the ""high affinity'' receptor sites. Other lectins (wheat germ agglutinin, Dolichos) and enzymes (alpha-L-fucosidase, beta-N-acetyl-hexosaminidase and neuraminidase) are without effect on insulin binding. Comparative studies performed on diabetic mouse liver membrane (KK mice), previously characterized by decreased number of insulin receptors, are in good agreement with qualitatively similar receptor sites in both non-diabetic (control) and diabetic mice. Effects of enzymes and lectins yielded same results as compared to control membranes. Plasma membrane proteins and glycoproteins in both types of mouse are indistinguishable with respect to enzymic and chemical analysis. Sodium dodecyl sulphate acrylamide gel electrophoresis shows identical patterns. Moreover, the decrease in the number of insulin receptors is easily reversed with diet restriction. These data are consistent with the similarity of receptor sites in control and diabetic liver membrane.
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PMID:Involvement of glycoconjugates in insulin-receptor interactions. Studies in liver plasma membranes of control and diabetic mice. 69 17

The asg mutants of Myxococcus xanthus are defective in the production of an extracellular substance, called A-factor, that is required for expression of a set of fruiting body-specific genes. A-factor is released by wild-type cells (asg+) after 1 to 2 h of development. When A-factor is added to asg mutant cells, it restores expression of their A-factor-dependent genes. Rescue of beta-galactosidase production in an asg mutant carrying the A-factor-dependent lacZ transcriptional fusion (omega 4521) was used to assay A-factor activity. According to this assay, two types of substances with A-factor activity are present in conditioned medium. One type is heat stable and of low molecular weight; the other is heat labile and of high molecular weight. An approximately 27-kDa protein with heat-labile A-factor activity was purified from conditioned medium. The purified protein has proteolytic activity as well as A-factor activity. The substrate specificity of the 27-kDa protease resembles that of trypsin. A smaller protein with both heat-labile A-factor activity and proteolytic activity was identified. Its substrate specificity differs from that of the 27-kDa protein. In addition, trypsin and other proteases were found to have heat-labile A-factor activity. Trypsin inhibitory protein from soybeans neutralizes the A-factor activity of trypsin in parallel with its neutralization of protease activity, showing that the proteolytic activity of trypsin is necessary for its A-factor activity. The 27-kDa protein rescues the aggregation and sporulation defects of an asgB mutant in submerged culture as well as its ability to express beta-galactosidase from an asg-dependent lac fusion.
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PMID:Proteins that rescue A-signal-defective mutants of Myxococcus xanthus. 157 96

Removal of sialic acid from the von Willebrand factor (vWF) subunit exposes additional cleavage sites in the amino-terminal region that are associated with loss of large multimers. The extent of large multimer loss was evaluated by examining the sites of subunit cleavage of native and carbohydrate-modified vWF after treatment with trypsin, chymotrypsin, or plasmin. In the presence of proteinase inhibitors, purified vWF was treated with neuraminidase alone to remove 90% to 95% of the sialic acid or with neuraminidase and beta-galactosidase to remove the sialic acid and 45% to 50% of the D-galactose, with little or no loss of large multimers observed. Digestion of native vWF with trypsin produced the greatest loss of large multimers, while chymotrypsin produced less and plasmin produced the least. Large multimer loss was more extensive with each enzyme after carbohydrate modification of vWF. The extent and approximate location of subunit cleavage was determined by immunoblotting and monoclonal antibody epitope mapping. Trypsin, chymotrypsin, and plasmin were shown to produce both amino- and carboxyl-terminal fragments. The number, location, and relative quantities of carboxyl-terminal fragments produced were unchanged after carbohydrate modification. However, digestion of the amino-terminal region was considerably more extensive after carbohydrate modification as judged by a marked decrease or absence of the larger fragments seen when native vWF was digested, and by the appearance of new smaller molecular mass species. Therefore, the greater loss of large multimers that occurs after carbohydrate modification is likely to be the result of cleavages in the amino-terminal region of the molecule. By protecting the vWF subunit against amino-terminal cleavage, sialic acid inhibits the loss of large multimers.
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PMID:Sialic acid prevents loss of large von Willebrand factor multimers by protecting against amino-terminal proteolytic cleavage. 246 Jan 62

In order to know if the beta-galactosidase of the rat epididymal fluid, as other secreted acid hydrolases, carries a marker in its molecule, we studied the binding of this enzyme to cellular membranes of the epididymal tissue. The binding, like that mediated by the phosphomannosyl receptor, was saturable, did not require calcium, had a Kd in the nM range and was inhibited by phosphatase or metaperiodate treatment of the enzyme. However fructose 6-phosphate derivates were more effective competitive inhibitors than mannose 6-phosphate. The binding capacity of the membranes were extractable with Triton X-100 and incorporable into liposomes. Trypsin inhibited the binding capacity of Triton extracts but it did not affect the affinity of intact cellular membranes for beta-galactosidase. The results suggest that a phosphorylated carbohydrate of the enzyme is bound by a recognizing site of the cellular membranes different from the phosphomannosyl receptor.
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PMID:beta-Galactosidase from rat epididymal fluid is bound by a recognition site attached to membranes of the epididymis different from the phosphomannosyl receptor. 303 84

A hybrid protein of Escherichia coli, exhibiting both adenylate cyclase and beta-galactosidase activities, was purified and characterized. This protein, obtained by genetic engineering, contained the first 556 amino acids of adenylate cyclase connected to the eighth-residue of beta-galactosidase through a pentapeptide Val-Gly-Asp-Pro-Val. The fusion protein was less stable than the native beta-galatosidase. Trypsin cleaved preferentially the adenylate cyclase moiety of the hybrid protein at a ratio of 1/50 (w/w). The kinetic properties of the hybrid protein were comparable, with a few exceptions, to those of native adenylate cyclase and beta-galactosidase. 'Truncated' adenylate cyclase was no longer sensitive to inhibition by excess ATP, which seems to indicate a second nucleotide binding site of wild-type adenylate cyclase. Photoirradiation of the hybrid protein with 8-azidoadenosine 5'-triphosphate inactivated the adenylate cyclase activity, leaving intact the beta-galactosidase activity. A radiolabeled ATP analog was incorporated after photoirradiation into the adenylate cyclase moiety of the fusion protein as shown by limited digestion with trypsin.
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PMID:Characterization of a beta-galactosidase hybrid protein carrying the catalytic domain of Escherichia coli adenylate cyclase. 309 31

Antibody response and protection against Ehrlich ascites tumor (EAT) was studied in eight EAT-immunized strains of mice (AL/N, BALB/C, C57BL/6J, F1 (C57BL/6 x BALB/C), C57BL/10J, B10.BR, CBA/Ca, SW). The results showed a close association between IgM response and resistance to subsequent tumor challenge. Thus, protection was only achieved in those animals giving a measurable IgM response against EAT cell surface antigens, i.e., all inbred strains of mice tested, except CBA/Ca, and some outbred SW mice. The lack of IgM response to these antigens in CBA/Ca was not linked to the strain H-2 haplotype. Resistance could be passively transferred to nonimmunized mice by means of serum, or purified IgM, from protected immune animals. Moreover, complement depletion by cobra venom factor treatment did not modify the protection afforded to those mice. IgM reactivity to EAT cells was completely abolished by previous cell trypsinization. Trypsin removed but did not destroy the antigen(s) recognized by the IgM, since all its activity could be absorbed with the supernatant of the EAT cell trypsinization. Absorption assays with this supernatant treated with different agents, showed that lipids, simple peptides and nucleic acids were not important components of the antigenic determinants. On the contrary, its susceptibility to beta-galactosidase and particularly to a mild periodate oxidation, suggested that determinants recognized by the IgM against the EAT cell surface are carbohydrate in nature.
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PMID:IgM response and resistance to ascites tumor growth. 366 33

Previous studies have shown that the mechanism of spontaneous aggregation of Streptococcus mitis ATCC 903 depends on a lectin-ligand type interaction. To study the specificity of the ligand, the binding of a number of lectins of different sugar specificities to the surface of untreated, trypsin and beta-galactosidase-treated bacteria was studied by assessing aggregation. Untreated bacteria were rapidly aggregated by concanavalin A (Con A), wheat-germ agglutination (WGA) and helix pomatia lectin (HPL). Other lectins tested, e.g. peanut agglutinin and soy bean lectin, did not induce aggregation. Lectin-induced aggregation was distinguished from the spontaneous one by recording the course of aggregation and inhibition of lectins by specific sugars. Trypsin-treated bacteria lost their ability for both spontaneous and lectin-induced aggregation. beta-galactosidase-treated bacteria were aggregated only in the presence of Con A and HPL. The bacteria retained their ability for spontaneous aggregation after removal of lectins and inhibitory sugars. These findings suggest that ligand is of glycoprotein nature, since it was removed from the bacterial surface by treatment with trypsin, as shown by the inability of treated cells for both spontaneous and lectin-induced aggregation. Partial degradation of the carbohydrate part of the ligand is indicated by the ability of beta-galactosidase-treated bacteria to aggregate in the presence of Con A and HPL.
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PMID:Binding of lectins to Streptococcus mitis cells. Studies of the specificity of ligand mediated aggregation. 392 Aug 67


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