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)

1. When Escherichia coli leu(-) was incubated at 35 degrees in a medium based on minimal medium, but with the omission of phosphate ions, or glucose, or NH(4) (+) ions and leucine, intracellular protein was degraded at a rate of about 5%/hr. in each case. If Mg(2+) ions were omitted, however, the rate of degradation was 2.9%/hr. 2. Under certain conditions of incubation, protein degradation was inhibited. The inhibitor was neither NH(4) (+) ions nor amino acids, and its properties were not those of a protein, but it might be an unstable species of RNA. 3. Although a large part of the cell protein was degraded at about 5%/hr. during starvation of NH(4) (+) ions and leucine, some proteins were lost at more rapid rates, whereas others were lost at lower rates or not at all. 4. In particular, beta-galactosidase activity was lost at about 8%/hr. during starvation of NH(4) (+) ions and leucine, whereas d-serine-deaminase and alkaline-phosphatase activities were stable. During starvation of Mg(2+) ions, all three enzyme activities were stable.
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PMID:Intracellular protein breakdown in non-growing cells of Escherichia coli. 534 Mar 66

Monoclonal antibodies were raised against two soluble, galactose-binding lectins from cells of Dictyostelium discoideum, discoidin I and II. These antibodies reacted not only with both discoidins, but also with a plasma membrane glycoprotein of aggregation competent cells, called contact site A, and with two carbohydrate-binding proteins of E. coli, beta-galactosidase and lac repressor. The possibility that the antibody recognizes a structure common to different carbohydrate-binding proteins is discussed. The two carbohydrate-binding proteins of E. coli share with discoidin I the sequence -Ser-X-X-Ile-His(Pro)-Pro(His)-Leu-Thr- which might be responsible for the cross-reactivity.
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PMID:Monoclonal antibody against cytoplasmic lectins of Dictyostelium discoideum: cross-reactivity with a membrane glycoprotein, contact site A, and with E. coli beta-galactosidase and lac repressor. 620 16

The amino-terminal sequence of the Tn3 transposase protein was determined to be Pro-Val-Asp-Phe-Leu-Thr-Thr-Glu-Gln-Val-Glu-Ser.... This was determined both from an active transposase protein purified from a transposase overproducing mutant strain and from a hybrid transposase-beta-galactosidase fusion protein. The amino acid sequence corresponded to the DNA sequence of the transposase gene beginning at an ATG initiation codon, as previously predicted from the analysis of transposase-beta-galactosidase gene fusions.
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PMID:Amino-terminal sequence of the Tn3 transposase protein. 627 48

The natural history of the mannose 6-phosphate receptor was examined by radiolabeling cells in monolayers or in suspension; the receptor was isolated by immuno- or affinity precipitation followed by polyacrylamide gel electrophoresis. The receptor was found to contain asparagine-linked oligosaccharide chains and phosphorylated serine residues. Newly made receptor was sensitive to endo-beta-N-acetylglucosaminidase H (endo-H) and was slowly converted to a mature endo-H resistant form; phosphate was found on the mature receptor only. The receptor had an apparent molecular weight of 215,000 at all times, as determined under reducing and denaturing conditions; unreduced receptor had a greater electrophoretic mobility, suggesting the presence of intrachain disulfide linkages. The synthesis of immunoreactive receptor occurred with a lag of 50 min and of functional receptor with a lag of 70 min, indicating a requirement for some post-translational event(s) for acquisition of immunoreactivity and binding activity. Maturation of asparagine-linked oligosaccharides was not the requisite modification, since endo-H sensitive or deglycosylated receptor bound to both antibody and to insoluble phosphomannan; however, much less immunoreactive and functional receptor was detected in the presence of tunicamycin. Immunoprecipitable [3H]leucine-labeled receptor was degraded with a t1/2 of 16 h and 6 h for cells in monolayers and suspension, respectively, whereas 32P was lost with a corresponding t1/2 of 2.3 and 4 h. A pool of cell surface mannose 6-phosphate receptor was identified by separation on Percoll gradients as well as by iodination of cells with 125I; receptor in this pool was resistant to endo-H and had a t1/2 similar to that of the total [3H]leucine-labeled receptor, even in the presence of a saturating concentration of ligand. During endocytosis, ligand (beta-galactosidase) and 125I-receptor separated, the ligand accumulating within lysosomes. These results are consistent with current concepts of recycling of the mannose 6-phosphate receptor.
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PMID:Biosynthesis and turnover of the mannose 6-phosphate receptor in cultured Chinese hamster ovary cells. 630 79

Pseudorevertants able to use L-leucyl-L-leucyl-L-leucine as a leucine source have been isolated from a Salmonella typhimurium strain carrying stable (nonreverting) mutations in pepN, pepA, and pepB. These strains carry mutations at a locus pto (peptidase T overproducer) tightly linked to pepT that cause an elevated expression of the tripeptidase peptidase T. An F' episome carrying the pto and pepT loci has been constructed and used to show that the pto mutations are cis dominant. Expression of beta-galactosidase from a Mu d1(Apr lac) insertion in pepT is increased by pto mutations. The pto mutations, therefore, define a site affecting the transcription of pepT.
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PMID:Overproduction of Salmonella typhimurium peptidase T. 631 18

The promoter and translation initiation region of the Saccharomyces cerevisiae leu2 gene was fused to the Escherichia coli beta-galactosidase gene. This fusion located the control region of the leu gene and orientated its direction of expression. When the fusion was placed into yeast cells, beta-galactosidase was expressed under the same regulatory pattern as the original leu2 gene product: its synthesis was repressed in the presence of leucine and threonine. Sensitive chromogenic substrates for beta-galactosidase were used to detect expression in isolated colonies growing on agar medium. Mutant yeast cells with increased beta-galactosidase activity were identified by the color of the colonies they formed. One class of mutants obtained appeared to affect ars1 plasmid maintenance, and another class appeared to affect beta-galactoside uptake.
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PMID:Fusion of the Saccharomyces cerevisiae leu2 gene to an Escherichia coli beta-galactosidase gene. 640 36

Aging is assumed to decrease lysosomal enzyme release from polymorphonuclear leukocytes (PMN). A synthetic chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) was utilized to stimulate enzyme release of PMN from 45 human subjects, 21 males and 24 females, ranging in age from 22-83 yr old. Results of the studies showed no sex differences in the stimulation of enzyme release for either age group. However, stimulation was found to significantly decline in both males and females over 50 yr old compared to subjects under 50 yr old. The linear formulae for beta-glucuronidase, beta-galactosidase and lysozyme in male subjects were Y = 6.5X + 617.2, Y = -1.9X + 311.5 and Y = -1.9X + 327.3 with correlation coefficient of -0.685, -0.352 and -0.401, respectively. The linear formulae in females were Y = -5.2X + 536.6, Y = -3.0X + 340.6 and Y = -1.7X + 333.6 with correlation coefficient of -0.582, -0.303 and -0.462, respectively. These findings suggest that there was an age-related decline of response to the stimulant, fMet-Leu-Phe.
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PMID:Age-related decline in lysosomal enzyme release from polymorphonuclear leukocytes after N-formyl-methionyl-leucyl-phenylalanine stimulation. 642 Jan 76

The nature of the molecular defect resulting in the beta-galactosidase deficiency in different forms of GM1-gangliosidosis and mucopolysaccharidosis IV B (Morquio B syndrome) was investigated. Normal and mutant cultured skin fibroblasts were labeled in vivo with [3H]leucine and immunoprecipitation studies with human anti-beta-galactosidase antiserum were performed, followed by polyacrylamide gel electrophoresis and fluorography. In Morquio B syndrome, the mutation does not interfere with the normal processing and intralysosomal aggregation of beta-galactosidase. In cells from infantile and adult GM1-gangliosidosis, 85-kDa precursor beta-galactosidase was found to be synthesized normally but more than 90% of the enzyme was subsequently degraded at one of the early steps in posttranslational processing. The residual 5-10% beta-galactosidase activity in adult GM1-gangliosidosis is 64-kDa mature lysosomal enzyme with normal catalytic properties but with a reduced ability of the monomeric form to aggregate into high molecular weight multimers. Knowledge of the exact nature of the molecular defect underlying beta-galactosidase deficiency in man may lead to a better understanding of the clinical and pathological heterogeneity among patients with different types of GM1-gangliosidosis and Morquio B syndrome.
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PMID:Processing of human beta-galactosidase in GM1-gangliosidosis and Morquio B syndrome. 642 Apr 16

Beta-Galactosidase is rapidly inactivated by iodination catalyzed by lactoperoxidase but is not inactivated in the presence of the substrate analogue, isopropyl beta-D-thiogalactoside (IPTG). Enzyme activity is lost upon the incorporation of 1 mol of iodine per mol of monomer, without dissociation of the tetrameric structure. Tryptic digests of beta-galactosidase iodinated with 125I in the presence and absence of IPTG were separated by high-performance liquid chromatography and were compared. One fraction was found to be more highly labeled in the digest from the inactivated protein. After isolation of the peptide, amino acid analysis indicated it to be Asp-Tyr-Leu-Arg, residues 252-255. Thus, Tyr-253 is the most reactive tyrosine in beta-galactosidase. This suggests that the conformation of this region of the protein may be altered by binding of IPTG to make Tyr-253 less accessible to iodination. Alternatively, Tyr-253 could be an active-site residue.
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PMID:Inactivation of beta-Galactosidase by iodination of tyrosine-253. 681 83

Amylase, alpha- and beta-glucosidase, alpha- and beta-galactosidase, beta-fructosidase, trypsin, aminotripeptidase, leucine-aminopeptidase, prolinase, prolidase glycyl-L-leucine dipeptidase and glygylglycine dipeptidase are present in the 3rd instar larvae of Chilo auricilius.
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PMID:Digestive enzymes in the gut and salivary gland of the larvae of Chilo auricilius Ddgn. 698 21


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