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 expression vector lambda gt11Amp3 has been used to construct a cDNA library from rat liver polyadenylated RNA. Clones expressing antigenic determinants for rat albumin, transferrin, transthyretin, apolipoprotein E and apolipoprotein AII have been identified. Albumin clones containing cDNA inserts ranging from 0.9 kb to 1.9 kb were further identified by restriction mapping and nucleic acid sequencing. The largest insert contained the entire coding sequence for albumin. Characterization of the expressed proteins by acrylamide gel electrophoresis followed by immunological detection indicated that the proteins were produced as hybrids linked to the bacterial beta-galactosidase. A cDNA library for human liver polyadenylated RNA has also been constructed. Clones expressing antigenic determinants for human serum albumin, transferrin and apolipoproteins AI, AII, AIV and E have been isolated and their identity established by nucleotide sequencing and restriction mapping. Both rat and human serum protein cDNA clones are currently being used to study the tissue specific expression of serum proteins and for the isolation and characterization of the corresponding genes.
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PMID:Isolation and characterization of genes for blood proteins. 330 67

1. Three fractions of beta-galactosidase activity from the rat small-intestinal mucosa were separated chromatographically. Two of these fractions had an acid pH optimum at 3-4, and the third one had a more neutral pH optimum at 5.7. 2. The two ;acid' beta-galactosidase fractions had considerably lower K(m) values for hetero beta-galactosides than for lactose. The V(max.) values were similar for all the substrates used (lactose, phenyl beta-galactoside, o-nitrophenyl beta-galactoside, p-nitrophenyl beta-galactoside and 6-bromo-2-naphthyl beta-galactoside). No difference could be detected between the two ;acid' fractions with respect to their enzymic properties (pH optimum, K(m) for the different substrates, K(i) for lactose as an inhibitor of the hydrolysis of hetero beta-galactosides, K(i) for phenyl beta-galactoside as an inhibitor of the hydrolysis of lactose, and relative V(max.) for the hydrolysis of different substrates). These two fractions probably represent different forms of the same enzyme. 3. The ;neutral' fraction had similar K(m) values for all the substrates hydrolysed, but with lactose as substrate the V(max.) was much higher than with the hetero beta-galactosides. This fraction did not split phenyl beta-galactoside or 6-bromo-2-naphthyl beta-galactoside at a measurable rate. 4. Lactose was a competitive inhibitor of the hetero beta-galactosidase activities of all the three fractions, and K(i) for lactose as an inhibitor in each case was the same as K(m) for the lactase activity. Phenyl beta-galactoside was a competitive inhibitor of the lactase activity of all the three fractions. These facts strongly indicate that in all the three fractions lactose is hydrolysed by the same active sites as the hetero beta-galactosides. 5. Human serum albumin stabilized the separated enzymes against inactivation by freezing and thawing.
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PMID:Rat small-intestinal beta-galactosidases. Kinetic studies with three separated fractions. 572 84

The early renal function parameters (RFP), i.e. urinary alanine aminopeptidase (AAP), beta-galactosidase (beta GAL), N-acetyl-beta-D-glucosaminidase (NAG), retinol-binding protein (RBP), albumin (ALB), total protein (TP) and the conventional RFP plasma creatinine were assessed in 8 patients before and during treatment with the nephrotoxic antitumor agent cis-platin. Plasma creatinine increased during treatment with cis-platin. In all patients, acute tubular damage was revealed by early RFP. Albumin and total protein excretion patterns suggested alterations in glomerular function. The cumulative change in RBP excretion was related to plasma creatinine concentrations following cis-platin administration. The present study demonstrates that urinary RBP is a valuable parameter for the early assessment of cis-platin-induced nephrotoxicity.
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PMID:Comparison of renal function parameters in the assessment of cis-platin induced nephrotoxicity. 791 Jun 67

Xenoestrogens, such as o,p'-DDT and octyl phenol (OP), have been associated with reproductive abnormalities in various wildlife species. Xenoestrogens mimic the natural estrogen 17 beta-estradiol and compete for binding to the estrogen receptor. Even though the affinity of o,p'-DDT and OP for the estrogen receptor is approximately 1000-fold lower than 17 beta-estradiol, the actions of xenoestrogens could be enhanced if their bioavailability in serum were greater than 17 beta-estradiol. To test this hypothesis, the yeast estrogen screen (YES) was created by expressing human estrogen receptor (hER) and two estrogen response elements (ERE) linked to the lacZ gene. The beta-galactosidase activity of the YES system was significantly increased after treatment with 17 beta-estradiol or the xenoestrogens diethylstilbestrol (DES), o,p'-DDT, and OP but not with vehicle, antiestrogen ICI 164,384, dexamethasone, or testosterone. To determine whether serum proteins affected the bioavailability of natural estrogens compared to xenoestrogens, albumin, sex hormone binding globulin (SHBG), or charcoal-stripped serum were added to the YES system and beta-galactosidase activity assayed. Albumin and SHBG decreased beta-galactosidase activity in the presence of estradiol to a greater extent than DES, o,p'-DDT, and OP. Human and alligator charcoal-stripped serum were also effective at selectively reducing beta-galactosidase activity in the presence of estradiol compared to xenoestrogens. Human serum was more effective than alligator serum in reducing beta-galactosidase activity in the presence of xenoestrogens, indicating that serum may serve as a biomarker for sensitivity to xenoestrogens. Selective binding of 17 beta-estradiol by proteins in serum indicates that certain xenoestrogens may exert greater estrogenicity than originally predicted. The estrogenic potency of a compound involves its binding affinity, bioavailability in serum, and persistence in the environment. Our data demonstrate the utility of the YES system for identifying and characterizing environmental estrogens.
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PMID:A yeast estrogen screen for examining the relative exposure of cells to natural and xenoestrogens. 874 43