Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Free and total activities of beta-glucosidase, beta-galactosidase, N-acetyl-beta-glucosaminidase and beta-glucuronidase have been determined fluorimetrically in five subcellular fractions of rat kidney. 2. The beta-glucosidase activity appeared in the soluble fraction, beta-glucuronidase had the distribution pattern of a lysosomal enzyme, and both beta-galactosidase and N-acetyl-beta-glucosaminidase had bimodal distributions. 3. Two types of beta-galactosidase activity were found: a sedimentable type, having optimum pH3.7, mol.wt. about 80000 and slow electrophoretic mobility at pH7.0 in starch gel; and a soluble type of much faster mobility, having optimum pH5.5-6.5 and mol.wt. about 40000. 4. Evidence is presented that the beta-glucosidase and the soluble type of beta-galactosidase are the same enzyme. 5. Most of the N-acetyl-beta-glucosaminidase activity was in the lysosome-rich fractions, but a significant proportion occurred in the microsomal fraction in a non-latent form. 6. The use of beta-galactosidase and N-acetyl-beta-glucosaminidase as lysosomal marker enzymes is complicated by the possible presence of multiple forms, but this limitation does not apply to beta-glucuronidase in the rat kidney.
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PMID:The cellular distribution of some rat-kidney glycosidases. 558 24

The following enzymes of lysosomal origin were fluorimetrically determined in maternal plasma from the second to the ninth month of pregnancy at 1-mth intervals: beta-D-N-acetylglucosaminidase (EC 3.2.1.30), beta-D-glucuronidase (EC 3.2.1.31), beta-D-glucosidase (EC 3.2.1.21), beta-D-galactosidase (EC 3.2.1.22), alpha-D-galactosidase (EC 3.2.1.23), alpha-L-fucosidase (EC 3.2.1.51) and alpha-D-mannosidase (EC 3.2.1.24) (pH 4.0). As reference microsomal alpha-D-mannosidase (pH 5.7) was also studied. Thirty-eight healthy women, aged 18-37 yr, who had a normal pregnancy followed by normal parturition, were studied. All enzymes, with the only exception of beta-D-galactosidase, showed a progressive and statistically significant increase of activity throughout pregnancy. At the end of pregnancy, the increase ranged from a maximum of 5.6-fold for beta-D-N-acetylglucosaminidase to a minimum of 0.55-fold for alpha-D-mannosidase, pH 5.7. In the case of beta-D-N-acetylglucosaminidase, the level at the fifth month of pregnancy was significantly higher than that at the third month, and from the sixth to the ninth month each level significantly differed from that of the month immediately preceding.
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PMID:Behaviour of several enzymes of lysosomal origin in human plasma during pregnancy. 609 42

A human liver microsomal beta-glucosidase has been purified to apparent homogeneity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis where a single protein band of Mr 100,000 was obtained under reducing conditions. The enzyme was enriched about 73, 000-fold over starting microsomal membranes by polyethylene glycol fractionation, anion exchange chromatographies on DEAE-Trisacryl, and Mono Q followed by affinity chromatography on N-(9-carboxynonyl)-1-deoxynojirimycin-AH-Sepharose 4B. The purified enzyme had a pH optimum between 5.0 and 6.4, was activated by divalent metal ions, and required phospholipids for exhibition of activity. The enzyme catalyzed the hydrolysis of 3beta-D-glucosido-lithocholic and 3beta-D-glucosido-chenodeoxycholic acids with high affinity (Km, 1.7 and 6.2 microM, respectively) and of the beta-D-glucoside (Km, 210 microM) and the beta-D-galactoside of 4-methylumbelliferone. The ratio of relative reaction rates for these substrates was about 6:3:11:1. No activity was detectable toward 6beta-D-glucosido-hyodeoxycholic acid, glucocerebroside, and the following glycosides of 4-methylumbelliferone: alpha-D-glucoside, alpha-L-arabinoside, beta-D-fucoside or beta-D-xyloside. Immunoinhibition and immunoprecipitation studies using antibodies prepared against lysosomal glucocerebrosidase showed no cross-reactivity with microsomal beta-glucosidase suggesting that these two enzymes are antigenically unrelated.
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PMID:Purification and characterization of a microsomal bile acid beta-glucosidase from human liver. 911 Oct 29

A novel microsomal beta-glucosidase was recently purified and characterized from human liver that catalyzes the hydrolysis of bile acid 3-O-glucosides as endogenous compounds. The primary structure of this bile acid beta-glucosidase was deduced by cDNA cloning on the basis of the amino acid sequences of peptides obtained from the purified enzyme by proteinase digestion. The isolated cDNA comprises 3639 base pairs containing 524 nucleotides of 5'-untranslated and 334 nucleotides of 3'-untranslated sequences including the poly(A) tail. The open reading frame predicts a 927-amino acid protein with a calculated M(r) of 104,648 containing one putative transmembrane domain. Data base searches revealed no homology with any known glycosyl hydrolase or other functionally identified protein. The cDNA sequence was found with significant identity in the human chromosome 9 clone RP11-112J3 of the human genome project. The recombinant enzyme was expressed in a tagged form in COS-7 cells where it displayed bile acid beta-glucosidase activity. Northern blot analysis of various human tissues revealed high levels of expression of the bile acid beta-glucosidase mRNA (3.6-kilobase message) in brain, heart, skeletal muscle, kidney, and placenta and lower levels of expression in the liver and other organs.
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PMID:Molecular cloning and expression of human bile acid beta-glucosidase. 1148 89

Barley (Hordeum vulgare) seedlings contain five cyano glucosides derived from the amino acid L-leucine (Leu). The chemical structure and the relative abundance of the cyano glucosides were investigated by liquid chromatography-mass spectrometry and nuclear magnetic resonance analyses using spring barley cultivars with high, medium, and low cyanide potential. The barley cultivars showed a 10-fold difference in their cyano glucoside content, but the relative content of the individual cyano glucosides remained constant. Epiheterodendrin, the only cyanogenic glucoside present, comprised 12% to 18% of the total content of cyano glucosides. It is proposed that the aglycones of all five cyano glucosides are formed by the initial action of a cytochrome P450 enzyme of the CYP79 family converting L-Leu into Z-3-methylbutanal oxime and subsequent action of a less specific CYP71E enzyme converting the oxime into 3-methylbutyro nitrile and mediating subsequent hydroxylations at the alpha-, as well as beta- and gamma-, carbon atoms. Presence of cyano glucosides in the barley seedlings was restricted to leaf tissue, with 99% confined to the epidermis cell layers of the leaf blade. Microsomal preparations from epidermal cells were not able to convert L-[(14)C]Leu into the biosynthetic intermediate, Z-3-methylbutanal-oxime. This was only achieved using microsomal preparations from other cell types in the basal leaf segment, demonstrating translocation of the cyano glucosides to the epidermal cell layers after biosynthesis. A beta-glucosidase able to degrade epiheterodendrin was detected exclusively in yet a third compartment, the endosperm of the germinating seed. Therefore, in barley, a putative function of cyano glucosides in plant defense is not linked to cyanide release.
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PMID:Leucine-derived cyano glucosides in barley. 1211 61

Studies with purified mesophyll and epidermal protoplasts and bundle sheath strands have shown that the cyanogenic glucoside dhurrin (p-hydroxy-(S)-mandelonitrile-beta-d-glucoside) is localized in the epidermis of sorghum leaves whereas the enzymes involved in its degradation (dhurrin beta-glucosidase and hydroxynitrile lyase) are localized in the mesophyll tissue (Kojima M, JE Poulton, SS Thayer, EE Conn 1979 Plant Physiol 63: 1022-1028). The subcellular localization of these enzymes has now been examined using linear 30 to 55% (w/w) sucrose gradients by fractionation of mesophyll protoplast components. The hydroxynitrile lyase is found in the supernatant fractions suggesting a cytoplasmic (soluble cytoplasm, microsomal or vacuolar location). The dhurrin beta-glucosidase (dhurrinase) is particulate and mostly chloroplast-associated. The dhurrinase activity peak has a shoulder of activity more dense than that of the intact chloroplasts. This shoulder does not coincide with markers of any other cell fraction.In studies of chloroplasts isolated from ruptured mesophyll protoplasts by differential, low-speed centrifugation, the dhurrinase partitions in the same manner as the chloroplast marker triose phosphate dehydrogenase. Chloroplast localization of the beta-glucosidase has also been shown in histochemical studies using 6-bromo-2-naphthyl-beta-d-glucoside substrate coupled with fast Blue B.
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PMID:Subcellular Localization of Dhurrin beta-Glucosidase and Hydroxynitrile Lyase in the Mesophyll Cells of Sorghum Leaf Blades. 1666 25


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