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Query: KEGG:D03345 (beta-Galactosidase)
 434 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

beta-Galactosidase of Streptococcus lactis 7962 was partially purified, and its properties were studied. Enzyme from only this strain of numerous lactic streptococci tested was stable in cell exudates prepared by various means. Cell-free extracts of the 7962 strain were prepared by sonic treatment of washed cells previously grown in presence of lactose to fully induce enzyme synthesis. Protamine sulfate precipitation of the nucleic acids and ammonium sulfate precipitation of protein were used for partial purification of the enzyme. The resulting enzyme, when resuspended in cold (5 C) phosphate buffer, was extremely labile. However, ammonium sulfate in high concentrations (0.85 m) stabilized and stimulated beta-galactosidase activity. Sephadex G-200 gel filtration was used to achieve further purification and to monitor homogeneity of the enzyme. Separation of the beta-galactosidase in buffer at 5 C yielded an enzyme elution pattern showing two peaks of activity. However, addition of the enzyme solution in 0.85 m ammonium sulfate to the column equilibrated with the same salt concentration yielded only one peak of enzyme activity. The data suggested that the native enzyme was dissociating into active subunits which were stabilized in the presence of the ammonium sulfate.
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PMID:Purification and properties of Streptococcus lactis beta-galactosidase. 602 31

beta-Galactosidase has been purified from rabbit brain by a procedure which gives substantially greater purification and yield than the previously reported method. The enzyme was solubilized in 4% aqueous butanol and purified by a procedure which included affinity chromatography on columns of concanavalin A - Sepharose (ConA-Sepharose) and aminophenylthiogalactoside Sepharose (APT galactoside-Sepharose). The activity was resolved by DEAE-Sepharose chromatography into two fractions; the first did not bind to the column and was eluted in the unbound fraction, while the second bound to the column and could be eluted with a salt gradient. The unbound and bound fractions were purified 7600-fold and 4900-fold, respectively, by the newly developed procedure. Both gave two closely migrating protein bands on polyacrylamide gel electrophoresis and the major contaminating protein was beta-hexosaminidase in each case. The enzyme in the unbound fraction had an isoelectric point (pI) of 6.7 and an apparent molecular weight by gel filtration of 114 000 +/- 10 000. The enzyme that bound to DEAE-Sepharose at pH 8.0 and comprised about 60% of the total acid beta-galactosidase activity of rabbit brain eluted from Sephacryl S-200 as a single peak with apparent molecular weight 140 000 +/- 10 000. The two fractions displayed similar relative specific activities towards the synthetic substrates and ganglioside GM1 and lactosyl ceramide. Neither enzyme hydrolyzed galactosyl ceramide. We have immunological evidence which suggests that the two fractions of beta-galactosidase are also structurally related.
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PMID:Improved purification of beta-galactosidase from rabbit brain: two separable fractions share kinetic and structural properties. 641 4

A simple, sensitive and reproducible method of detection of extracellular beta-galactosidase was worked out. beta-Galactosidase secreted by the callus culture, or the roots of sprouting plants, hydrolyzes the substrate (6-bromo-2-naphthyl-beta-D-galactopyranoside) to produce beta-D-galactose and 6-bromo-2-naphthol, which after simultaneous azocoupling with hexazotized p-rosaniline, or basic fuchsine, produce a reddish brown compound, nearly insoluble in water (a diazonium salt). The colouring under the callus culture and around it, as well as the colouring of the roots of the sprouting plants, is a manifestation of the activity of extracellular beta-galactosidase by the objects under study. The intensity of the colouring is a measure of their enzymatic activity. The share of intracellularly localized enzyme represents the majority and the share of extracellular beta-galactosidase the minority.
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PMID:[Detection of secretion of beta-galactosidase by plant cells]. 1095 59

Hybridization to a PCR product derived from conserved betaine choline carnitine transporter (BCCT) sequences led to the identification of a 3.4-kb Sinorhizobium meliloti DNA segment encoding a protein (BetS) that displays significant sequence identities to the choline transporter BetT of Escherichia coli (34%) and to the glycine betaine transporter OpuD of Bacillus subtilis (30%). Although the BetS protein shows a common structure with BCCT systems, it possesses an unusually long hydrophilic C-terminal extension (169 amino acids). After heterologous expression of betS in E. coli mutant strain MKH13, which lacks choline, glycine betaine, and proline transport systems, both glycine betaine and proline betaine uptake were restored, but only in cells grown at high osmolarity or subjected to a sudden osmotic upshock. Competition experiments demonstrated that choline, ectoine, carnitine, and proline were not effective competitors for BetS-mediated betaine transport. Kinetic analysis revealed that BetS has a high affinity for betaines, with K(m)s of 16 +/- 2 microM and 56 +/- 6 microM for glycine betaine and proline betaine, respectively, in cells grown in minimal medium with 0.3 M NaCl. BetS activity appears to be Na(+) driven. In an S. meliloti betS mutant, glycine betaine and proline betaine uptake was reduced by about 60%, suggesting that BetS represents a major component of the overall betaine uptake activities in response to salt stress. beta-Galactosidase activities of a betS-lacZ strain grown in various conditions showed that betS is constitutively expressed. Osmotic upshock experiments performed with wild-type and betS mutant cells, treated or not with chloramphenicol, indicated that BetS-mediated betaine uptake is the consequence of immediate activation of existing proteins by high osmolarity, most likely through posttranslational activation. Growth experiments underscored the crucial role of BetS as an emerging system involved in the rapid acquisition of betaines by S. meliloti subjected to osmotic upshock.
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PMID:BetS is a major glycine betaine/proline betaine transporter required for early osmotic adjustment in Sinorhizobium meliloti. 1197 94

The reverse micellar system of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane was used for the extraction and primary purification of beta-galactosidase (EC 3.2.1.23) from the aqueous extract of barley (Hordeum vulgare) for the first time. The process parameters such as the concentration of the surfactant, the volume of the sample injected, and its protein concentration, pH, and ionic strength of the initial aqueous phase for forward extraction, buffer pH, and salt concentration for back extraction are varied to optimize the extraction efficiency. Studies carried out with both phase transfer and injection mode of reverse micellar extraction confirmed the injection mode to be more suitable for beta-galactosidase extraction. The extent of reverse micellar solubilization of proteins increased with an increase in protein concentration of the feed sample. However, back extraction efficiency remained almost constant (13-14.4%), which indicates the selectivity of AOT reverse micelles for a particular protein under given experimental conditions. beta-Galactosidase was extracted with an activity recovery of 98.74% and a degree of purification of 7.2-fold.
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PMID:Reverse micellar extraction of beta-galactosidase from barley (Hordeum vulgare). 1848 Sep 74