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 beta-galactosidase activity in extracts of Trichomonas foetus is separable into two fractions by gel filtration on Sephadex G-200. When o-nitrophenyl beta-d-galactoside is used as substrate the first fraction to be eluted, beta-galactosidase 1, has 50 times the activity (units per mg of protein) of the crude preparation. This fraction is activated by Mn(2+) and Co(2+) and inhibited by Hg(2+) and EDTA. In the presence of Mn(2+) the pH optimum for the hydrolysis of o-nitrophenyl beta-d-galactoside or lactose is 5.8-6.0. beta-Galactosidase 1 is an exoglycosidase that releases beta-linked galactose joined to aliphatic and various carbohydrate aglycones. Hydrolysis is prevented, however, by a substituent on either the subterminal sugar or the terminal non-reducing beta-galactosyl residue in an oligosaccharide. The second fraction, beta-galactosidase 2, is not activated by metal ions or inhibited by EDTA and has a broad pH optimum from 4.5 to 6.0.
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PMID:Enzymes of Trichomonas foetus. Separation and properties of two beta-galactosidases. 498 88

beta-Galactosidase (beta-gal, EC 3.2.1.23) and beta-D-phosphogalactoside galactohydrolase (beta-Pgal) activities were observed in all of 13 Lactobacillus species studied except L. casei and L. buchneri. Only the latter enzyme was detected in nine strains of L. casei. The beta-gal from L. thermophilus and the beta-Pgal from L. casei were purified and characterized. In comparison with beta-gal, the beta-Pal was slightly less active (V(max) values were 28.9 and 50.0 mumoles per mg per min, respectively), but the substrate affinitives were similar (K(m) values were 1.69 x 10(-3) M and 1.59 x 10(-3) M, respectively). Although the two enzymes had similar amino acid compositions, the molecular weight of beta-gal was 5.4 x 10(5) and that of beta-Pgal was 1.3 x 10(5). The beta-gal from L. thermophilus and the beta-Pgal from L. casei had optimal temperature and pH activity values of 55 C at pH 6.2 and 37 C at pH 5.0, respectively. The complete absence of beta-gal from a homofermentative Lactobacillus species of industrial importance is further evidence of the heterogeneity of this genus.
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PMID:Lactose-hydrolyzing enzymes of Lactobacillus species. 505 73

Differentiation of Salmonella from other gram-negative bacilli requires several biochemical and serological tests. A simplified 24-hr screening procedure has been devised which allows discarding of large numbers of isolates (picked from selective plating media) before they are subjected to this extensive testing. Cultures of gram-negative organisms isolated to triple sugar-iron slants during routine examination of products for Salmonella were tested for the presence of beta-galactosidase and Salmonella flagellar antigens. beta-Galactosidase-positive cultures which did not agglutinate in polyvalent flagellar antiserum were considered to be nonsalmonellae. Of 1,103 Salmonella cultures tested, none of the 61 different serotypes was missed by this procedure, whereas 673 (82.3%) of 818 nonsalmonellae were excluded from further testing. This screening procedure eliminates most nonsalmonellae and augments the proportion of cultures undergoing further biochemical and serological testing which will be confirmed as Salmonella.
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PMID:Salmonella screening procedure with tests for beta-galactosidase and flagellar antigens. 554 97

1. beta-Galactosidase activity was studied in homogenates and isolated microvilli fraction of jejunal mucosa from 14-day-old suckling rats. o-Nitrophenyl beta-d-galactoside served as the substrate. 2. The microvilli fraction contains about one-third of the total activity of the original homogenate. 3. The pH optimum of the beta-galactosidase was 3.5 in the total homogenate and supernatant fraction, whereas in the microvilli fraction the maximum activity was at pH5.5. 4. This work gives further support to the view that two beta-galactosidases exist in the jejunal mucosa.
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PMID:Activity of beta-galactosidase in homogenates and isolated microvilli fraction of jejunal mucosa from suckling rats. 589 Dec 19

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, alpha-D-mannosidase, alpha-L-fucosidase and N-acetyl-beta-D-glucosaminidase activities were assayed in serum and urine from rats treated with three different doses of the nephrotoxic antibiotic tobramycin (100 mg/kg/day for 5 days, 10 mg/kg/day for 10 days and 5 mg/kg/day for 20 days) and gentamicin (100 mg/kg/day for 5 days). A significant increase of beta-galactosidase, N-acetyl-beta-D-glucosaminidase and alpha-L-fucosidase activities occurred in urine following the administration of high doses of antibiotic. The enzyme activity was dependent on the dose level used. The excretion of alpha-D-mannosidase was atypical and elevated activities were observed on some days but no pattern of excretion of this enzyme was established. No change in any of the four glycosidase activities was found in serum of treated rats. The results obtained when high doses of gentamicin were employed are similar to those obtained with a similar dose of tobramycin. These results indicate that the assay of urinary glycosidase activities provides a useful method for monitoring the nephrotoxicity of antibiotics.
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PMID:Effect of tobramycin and gentamicin on the activity of some glycosidases in rat serum and urine. 615 73

beta-Galactosidase purified to apparent homogeneity from human placenta occurred in two separable fractions. A low molecular mass form (relative mass (Mr) 170 000) is composed of a single polypeptide chain (Mr 70 000). This was derived from a larger form by molecular sieve chromatography at both low (10 mM) and high (500 mM) NaCl concentration. The larger form of beta-galactosidase also contains small amounts of two polypeptides with apparent Mr values of 23 000 and 35 000 daltons. Both forms of the enzyme hydrolyze synthetic aryl galactosides and natural glycolipid substrates at comparable rates. Antibodies raised in rabbits against the low Mr beta-galactosidase also cross-reacts with the high Mr enzyme. The antibody preparation also cross-reacted with beta-hexosaminidase even though the latter was found at very low levels in the antigen, as judged by lack of detection of representative protein bands on sodium dodecyl sulfate - polyacrylamide gel electrophoresis and enzyme activity measurements. A portion of this cross-reactivity (35%) against beta-hexosaminidase could not be absorbed from the preparation without the simultaneous loss of beta-galactosidase activity, suggesting that the two enzymes show a degree of antigenic identity.
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PMID:Human placental beta-galactosidase: structural and immunological observations. 620 36

The total protein content and the activities of lysosomal hydrolases (arylsulphatase, alkaline and acid phosphatases, beta-glucuronidase, beta-N-acetylhexosaminidase, alpha-L-fucosidase and beta-galactosidase) in the uteri of ovariectomized rabbits treated with different concentrations of progesterone, oestradiol-17 beta and a combination of progesterone and oestradiol were determined. The enzyme activities were also measured in the reproductive organs of rabbits induced to superovulate by PMSG and hCG. In superovulated and steroid-treated rabbits, the changes in lysosomal hydrolases were more obvious in the endometrium than the myometrium. Except for the myometrial alkaline phosphatase and beta-galactosidase and the endometrial alkaline phosphatase, there were no significant changes in the solubilities of hydrolases after treatment with steroids. beta-Galactosidase levels were significantly higher in the ovariectomized rabbits treated with progesterone. An antagonistic effect of oestradiol and progesterone was observed with respect to uterine weight, protein content and enzyme activities in the ovariectomized rabbits treated simultaneously with oestradiol and progesterone.
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PMID:Hormonal regulation of lysosomal hydrolases in the reproductive tract of the rabbit. 622 Jan 45

Aspergillus fumigatus secretes a number of glycosidases into the culture medium when the cells are grown in a mineral salts medium containing guar flour (a galactomannan) as the carbon source. At least some of these glycosidases have been reported to be glycoproteins having N-linked oligosaccharides. In this study, we examined the effect of the glycoprotein processing inhibitor, castanospermine, on the structures of the N-linked oligosaccharides and on the secretion of various glycosidases. Cells were grown in the presence of various amounts of castanospermine; at different times of growth, samples of the media were removed for the measurement of enzymatic activity. Of the three glycosidases assayed, beta-hexosaminidase was most sensitive to castanospermine; and its activity was depressed 30 to 40% at 100 micrograms of alkaloid per ml and even more at higher alkaloid concentrations. On the other hand, beta-galactosidase activity was hardly diminished at castanospermine levels of up to 1 mg/ml, but significant inhibition was observed at 2 mg/ml. beta-Galactosidase was intermediate in sensitivity. Cells were grown in the presence or absence of castanospermine and labeled with [2-3H]mannose, [6-3H]glucosamine, or [1-3H]galactose to label the sugar portion of the glycoproteins. The secreted glycoproteins were digested with pronase to obtain glycopeptides, and these were identified on Bio-Gel P-4 (Bio-Rad Laboratories). The glycopeptides were then digested with endoglucosaminidase H to release the peptide portion of susceptible structures, and the released oligosaccharides were reisolated and identified on Bio-Gel P-4. The oligosaccharides from control and castanospermine-grown cells were identified by a combination of enzymatic and chemical studies. In control cells, the oligosaccharide appeared to be mostly Man8GlcNAc and Man9GlcNAc, whereas in the presence of alkaloid, the major structures were Glc3Man7GlcNAc and Glc3Man8GlcNAc. These data fit previous observations that castanospermine inhibits glucosidase I.
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PMID:Effect of castanospermine on the structure and secretion of glycoprotein enzymes in Aspergillus fumigatus. 623

Hybrid genes between the Escherichia coli lacZ gene and the iso-1-cytochrome c (CYC1) gene of Saccharomyces cerevisiae were constructed by recombination in vitro. Each of the hybrid genes encodes a chimeric protein with a cytochrome c moiety at the amino terminus and an active beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) moiety at the carboxy terminus. When these hybrids are introduced into S. cerevisiae on plasmid vectors, they direct synthesis of beta-galactosidase. beta-Galactosidase levels directed by one such plasmid display the pattern of regulation normally seen for cytochrome c (i.e., a reduction of synthesis in cells grown in glucose). This plasmid contains one codon of CYC1 fused to lacZ, and the fused gene is preceded by the 1100 nucleotides that lie upstream from CYC1. An analysis of deletions in the upstream DNA suggests that sequences required for efficient transcription initiation of CYC1 lie within the DNA segment 250--700 base pairs upstream from the start of the CYC1 coding sequence. This region is at least 130 base pairs upstream from the "Hogness box" sequence that precedes the CYC1 coding sequence.
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PMID:Fusion of Escherichia coli lacZ to the cytochrome c gene of Saccharomyces cerevisiae. 626 67


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