Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

beta-N-Acetylglucosaminidase secreted by Entamoeba histolytica was extracted from the growth medium by affinity chromatography on CH-Sepharose 4 B coupled to p-aminophenyl-1-thio-beta-2-acetamido-2-deoxyglucopyranoside. The enzyme was further purified by isoelectric focusing, by sequential chromatography on DEAE-cellulose and Sephadex G-150, and by preparative disc gel electrophoresis. Chitobiose (betaGlcNAc1-4GlcNAc) derived from chitin as well as the oligosaccharides betaGlcNAc1-4 betaGlcUA1-3GlcNAc, betaGlcNAc1-4 betaGlcUA1-3 betaGlcAc1-4GlcUA, and betaGlcNAc1-4 betaGlc-UA1-3 betaGlcNAc1-4 betaGlcUA1-3 betaGlcNAc1-4GlcUA derived from hyaluronic acid were tested as potential physiological substrates. All these oligosaccharides are susceptible to action of beta-N-acetylglucosaminidase from E. histolytica. Under identical conditions chitobiose is cleaved 38-48 times faster than hyhyauronate oligosaccharides. No release of N-acetylglucosamine was observed when glycopeptides from ovalbumin were used as substrate. The pH optimum of hydrolase activity was 4.5 when chitobiose was used as substrate. Optimal hydrolysis of aluronate oligosaccharides was observed at pH 3.0 for trisaccharide and pH 2.0 for tetra- and hexasaccharide, respectively. Estimation of molecular weight by means of gel filtration gave values of 75 000. The isoelectric point was 5.02 beta-N-Acetylglucosaminidase from E. histolytica does not act on macromolecular chitin and hyaluronic acid.
Mol Biochem Parasitol 1983 Feb
PMID:Degradation of biogenic oligosaccharides by beta-N-acetyl-glucosaminidase secreted by Entamoeba histolytica. 630 11

Chorionic villi from first trimester and term human placentas have been incubated in vitro and shown to release the lysosomal enzymes, beta-hexosaminidase, alpha-glucosidase and beta-glucuronidase. There was negligible release of the cytoplasmic enzyme, lactate dehydrogenase, under the same conditions. The first trimester villi released proportionally more of their lysosomal enzyme content than did the term villi. Extracellular levels of beta-hexosaminidase were raised and those of alpha-glucosidase and beta-glucuronidase were lowered when tissue was incubated with 1 microM colchicine, suggesting that microtubules are involved in the control of lysosomal enzyme release from placental villi.
Mol Cell Biochem 1980 Dec 10
PMID:Secretion of lysosomal enzymes by human placental villi in vitro. 645 98

We used Chinese hamster ovary cells, a cell line of fibroblastic origin, to investigate whether lysosomes are an exocytic compartment. To label lysosomal contents, Chinese hamster ovary cells were incubated with the solute marker horseradish peroxidase. After an 18-h uptake period, horseradish peroxidase was found in lysosomes by cell fractionation in Percoll gradients and by electron microscope cytochemistry. Over a 24-h period, lysosomal horseradish peroxidase was quantitatively retained by Chinese hamster ovary cells and inactivated with a t 1/2 of 6 to 8 h. Lysosomes were radioiodinated in situ by soluble lactoperoxidase internalized over an 18-h uptake period. About 70% of the radioiodine incorporation was pelleted at 100,000 X g under conditions in which greater than 80% of the lysosomal marker enzyme beta-hexosaminidase was released into the supernatant. By one-dimensional electrophoresis, about 18 protein species were present in the lysosomal membrane fraction, with radioiodine incorporation being most pronounced into species of 70,000 to 75,000 daltons. After a 30-min or 2-h chase at 37 degrees C, radioiodine that was incorporated into lysosomal membranes and contents was retained in lysosomes. These observations indicate that lysosomes labeled by fluid-phase pinocytosis are a terminal component of endocytic pathways in fibroblasts.
Mol Cell Biol 1984 Feb
PMID:Chinese hamster ovary cell lysosomes retain pinocytized horseradish peroxidase and in situ-radioiodinated proteins. 670 May 91

Simultaneous or sequential treatment of rat adipocytes with neuraminidase plus beta-galactosidase decreased insulin binding by 43%. No modification was observed with either enzyme individually. alpha-Mannosidase enhanced insulin binding (38%), whereas beta-N-acetylglucosaminidase and alpha-L-fucosidase were ineffective. Lectins that interact with galactose (Ricinus communis I, RCAI), mannose, Lens culinaris agglutinin (LCA), Concanavalin A (Con A) or N-acetylglucosamine (wheat-germ agglutinin, WGA) decreased insulin binding by 43, 57, 59 and 85% respectively. Lectin inhibition was dose-dependent, saturable and prevented by specific monosaccharides. RCAI, LCA, Con A and WGA decreased the insulin dissociation process by 45, 90, 78 and 84% respectively. Lectins specific for sialic acid, terminal galactose, N-acetylgalactosamine or fucose (Limulus polyphemus, peanut, soybean and Ulex I agglutinins) did not modify either insulin binding or dissociation. These results indicate involvement of penultimate D-galactose, internal N-acetyl-D-glucosamine and D-mannose residues in both processes. They suggest that, in rat adipocytes, a glycosidic moiety participates in the insulin-receptor interaction through N-linked oligosaccharides of the 'complex type'.
Mol Cell Endocrinol 1981 Sep
PMID:Further characterization of the insulin receptor glycosidic moiety in rat adipocytes. 679 21

Long-Evans Cinnamon (LEC) rats, characterized by a gross accumulation of hepatic Cu and the spontaneous onset of hepatitis, have been established to be an animal model for Wilson disease. They were used to estimate the relationships among copper (Cu), metallothionein (MT), and reduced glutathione (GSH) in biliary excretion in this study. Even though a huge amount of MT existed in the LEC rat liver (5016 micrograms/g liver) compared to that (63 micrograms/g liver) of controls (Fischer rats), the biliary excretion of MT (65 ng/ml bile) did not reflect the accumulated MT level in LEC rats. It seems likely that MT does not excrete intrinsically into the bile. Biliary excretion of Cu (0.17 microgram/ml) in LEC rats was significantly lower than that (0.57 microgram/ml) in Fischer rats. The difference in biliary excretion of GSH between the two groups was significant but slight. The reduced excretion of GSH into bile in LEC rats may be due to increased hepatic gamma-glutamyltransferase but not to hepatic GSH levels. There were no differences in biliary potassium and inorganic phosphorous between the two groups. On the other hand, excretion of lysosomal enzymes such as beta-N-acetylglucosaminidase into bile was much lower in LEC rats (15.6 units/liter) than in controls (42.5 units/liter). The defective biliary excretion of Cu may be due to impaired lysosomal exocytosis, rather than canalicular membrane impairment. The LEC rat is very useful for research into the dynamics of metal excretion via the hepatobiliary system.
Biochem Mol Med 1995 Jun
PMID:Biliary excretion of copper, metallothionein, and glutathione into Long-Evans Cinnamon rats: a convincing animal model for Wilson disease. 755 24

Tay-Sachs disease (TSD) results from a deficiency of beta-hexosaminidase A (EC 3.2.1.52) activity. A child with late-infantile TSD was found to have two HEXA mutations, 986 + 3A-->G (A-->G at the +3 position of intron 8) and 533G-->A, associated with the variant B1 form of TSD. We were able to detect exon 8-deleted, but no correctly spliced HEXA mRNA, from the non-533G-->A allele in this patient. This suggests that 986 + 3A-->G results in missplicing and, together with 533G-->A, TSD.
Biochem Mol Med 1995 Jun
PMID:An A-to-G mutation at the +3 position of intron 8 of the HEXA gene is associated with exon 8 skipping and Tay-Sachs disease. 755 30

Isoform patterns of six lysosomal glycosidases were studied in leukemic lymphoid cells phenotypically related to B and T cells at distinct stages of differentiation. In all types of cells, the activity of glycosidases under study was expressed in two major isoforms. No correlation was observed between isoform patterns and cell phenotypes. The beta-hexosaminidase isoform ratios for phenotypically related leukemic lymphoid cells but isolated from different sources (blood and spleen) differed. It was suggested that cell localization affects isoform expression. An anomalous alpha-mannosidase was detected in lymphoid cells from lymph nodes, while it was lacking in the phenotypically related blood lymphoid cells from the same patients. Isoform I of beta-hexosaminidase was recorded in lymphoid cells of patients with anemias.
Biochem Mol Biol Int 1994 Mar
PMID:Isoform patterns of lysosomal glycosidases in phenotypically different leukemic lymphoid cells. 803 17

Endo beta-N-acetylglucosaminidase activities were determined based on conversion of oligosaccharides containing two N-acetylglucosamines to the oligosaccharides with a single N-acetylglucosamine at the reducing terminal and following their separation on a carbohydrate analyzer. The oligosaccharides eluted from the high performance anion exchange column in the order of fucosyl-N,N'-diacetylchitobiose, N,N'-diacetylchitobiose and N-acetylglucosamine containing reducing terminals. Using this assay, differences in cleavage specificity of the endo beta-N-acetylglucosaminidase F (Endo F) activity on various free oligosaccharides obtained from the standard glycoproteins was determined. The commercial Endo F-peptide N-glycosidase/glycanyl amidase (PNGase) mixture readily cleaved high mannose and complex oligosaccharides (neutral and sialyated) with common core alpha 1-6 linked fucose found in porcine thyroglobulin including the trimannosyl-chitobiose core structure. However, the same Endo F mixture did not cleave the non-fucosylated complex oligosaccharides found in human transferrin and also the common core structure. Glycopeptide counterparts with and without fucose were good substrates for the endoglycosidases. These results show that the specificity of these enzymes is such that they can recognize the conformational differences between free oligosaccharides and glycopeptides with and without the common core alpha 1-6 linked fucose. In contrast, highly purified Endo F cleaved only the high mannose type oligosaccharides and was unable to cleave ovalbumin hybrid type oligosaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Recognit 1993 Sep
PMID:Endo beta-N-acetylglucosaminidase F cleavage specificity with peptide free oligosaccharides. 806 Jun 71

Sandhoff disease is an autosomal recessive lysosomal storage disease resulting from mutations of the HEXB gene encoding the beta subunit of beta-hexosaminidase A. Fibroblast lines from four patients with the infantile form of the disease were investigated for mutations by single strand conformation polymorphism analysis and direct sequencing of PCR products. Two of the cell lines were homozygous for a common, 16 kb deletion of the 5' end of HEXB gene. The two other cell lines contained the 16 kb deletion along with a second mutant allele generating a stop codon: in one case a nonsense mutation, C850-->T, which generated a stop codon at codon 284; and in the other, a single base deletion, delta T1344, which generated a stop codon at codon 451. One additional cell line investigated was a compound heterozygote for two frameshift mutations, delta G774 in exon 7 and delta AG1305-1306 in exon 11 (McInnes et al. 1992, Biochim. Biophys. Acta 1138: 315-317). Stop codons were generated in this cell line at codons 274 and 454, respectively. We took advantage of these genotypes to investigate the steady-state level of mRNA produced by cells containing stop codons using a competitive polymerase chain reaction technique. The mRNA levels were, as percent of normal per single gene dose: for the stop codon at codon 451, 30%; for those at codons 274 and 454, combined percentage of 1.7%; and at codon 284, 0.8%. These studies demonstrate a dramatic difference in the steady-state level of Hex beta mRNA in the cell lines with stop codons in close proximity to each other (codons 451 vs 454).(ABSTRACT TRUNCATED AT 250 WORDS)
Hum Mol Genet 1994 Jan
PMID:Impact of premature stop codons on mRNA levels in infantile Sandhoff disease. 816 15

Goats affected with beta-mannosidosis, an autosomal recessive disease of glycoprotein catabolism, have deficient tissue and plasma levels of the lysosomal enzyme beta-mannosidase. Pathological characteristics include cytoplasmic vacuolation in the nervous system and viscera, and myelin deficits that demonstrate regional variation. This study was designed to determine the correlation between beta-mannosidase activity in normal animals and the severity of lesions in affected goats, and to assess the regional changes in lysosomal enzyme activity in specific regions and cell types in affected animals. Although enzyme activity in normal organs (kidney, thyroid, brain) is correlated in general with the accumulation of uncatabolized substrate and with the extent of vacuolation, this correlation does not extend to assessment of specific regions of the central nervous system (CNS). In affected goats, the activities of alpha-mannosidase, alpha-fucosidase, and beta-hexosaminidase are elevated to a greater extent in all CNS regions than in organs. The results suggest cell-specific, organ-specific, and enzyme-specific regulation of changes in lysosomal enzyme activity in the presence of metabolic perturbations, such as deficiency of beta-mannosidase activity.
Mol Chem Neuropathol 1994 Jan
PMID:Biochemical and histochemical analysis of lysosomal enzyme activities in caprine beta-mannosidosis. 817 72


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