Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell-free extracts of a strain of Proteus vulgaris degrade NADH to reduced nicotinamide riboside, adenosine and two molecules of phosphate. The system is weakly active in fresh cell extracts, but activity is increased about 10-fold on rapid heating to 70-100 degrees C. On returning to room temperature, the activity returns rapidly to its initial low value but can be re-activated by again heating to 70-100 degrees C. Reversible activation can also be effected by extremes of pH or by teatment with 8M-urea. Activation appears to be due to reversible changes in conformation of the protein of the enzyme rather than to combination of the enzyme with a heat-labile inhibitor. The active form can be stabilized by addition of PPi. The system, which also possesses 5'-nucleotidase activity not separable from the NADH pyrophosphatase, requires Co2+ (0.4mM) for maximum activity. Although activated at relatively high temperatures, it is not enzymically active until cooled to 50-60 degrees C. It may be purified by affinity chromatography (with NAD+ as ligand) to an activity over 400 times that of the crude cell extract, and yields only one major band on polyacrylamide-gel electrophoresis.
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PMID:An enzyme degrading reduced nicotinamide-adenine dinucleotide in Proteus vulgaris. 21 47

1. Fragments (2-20 mg wet wt.) of closed needle-biopsy specimens from human liver were disrupted in iso-osmotic sucrose and subjected to low-speed centrifugation. The supernatant was layered on a linear sucrose-density gradient in the Beaufay small-volume automatic zonal rotor. The following organelles, with equilibrium densities (g/ml) and principal marker enzyme shown in parentheses, were resolved: plasma membrane (1.12-1.14; 5'-nucleotidase); lysosomes (1.15-1.20; N-acetyl-beta-glucosaminidase); mitochondria (1.20; malate dehydrogenase); endoplasmic reticulum (1.17-1.21; neutral alpha-glucosidase); peroxisomes (1.22-1.24; catalase). 2. The distribution of particulate alkaline phosphatase and, to a lesser degree, leucine 2-naphthylamidase followed that of 5'-nucleotidase. gamma-Glutamyltransferase was associated with membranes of significantly higher equilibrium density than was 5'-nucleotidase. 3. The distribution of 12 acid hydrolases was determined in the density-gradient fractions. beta-Glucosidase had a predominantly cytosolic localization, but the other enzymes showed a broad distribution of activity throughout the gradient. Evidence was presented for two populations of lysosomes with equilibrium densities of 1.15 and 1.20 g/ml, but containing differing amounts of each enzyme. Further evidence of lysosomal heterogeneity was demonstrated by studying the distribution of isoenzymes of hexosaminidase and of acid phosphatase. 4. The resolving power of the centrifugation procedure can be further enhanced with membrane perturbants. Digitonin (0.12 mM) selectively disrupted lysosomes, markedly increased the equilibrium density of plasma-membrane components and lowered the density of the endoplasmic reticulum, but did not affect the mitochondria or peroxisomes. Pyrophosphate (15 mM) selectively lowered the equilibrium density of the endoplasmic reticulum.
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PMID:Analytical subcellular fractionation of needle-biopsy specimens from human liver. 70 96

Coupled enzyme assays are described for measuring inorganic phosphates, organic phosphates and phosphate-liberating enzymes in biological material. The assays all determine Pi by its reaction with inosine, catalysed by nucleoside phosphorylase; this yields ribose 1-phosphate and hypoxanthine. The hypoxanthine is oxidized to uric acid by xanthine oxidase, and may be measured either by the absorbance of the uric acid, or by the formazan formed when a tetrazolium salt is used as the oxidant. The coupled enzyme assays are characterized by high sensitivity, quantitative utilization of phosphates and stoichiometric formation of the measurable products, measurement at pH 6.0-8.5, determination of phosphates within a single analytical step, and continuous measurement of phosphohydrolase activity in a corresponding rate assay. Examples include determinations of substrates such as Pi, PPi and AMP, and of enzymes such as 5'-nucleotidase, inorganic pyrophosphatase and glucose-6-phosphatase. Directions for further examples are given.
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PMID:Enzymic determination of inorganic phosphates, organic phosphates and phosphate-liberating enzymes by use of nucleoside phosphorylase-xanthine oxidase (dehydrogenase)-coupled reactions. 299 93

Isopycnic equilibration and sedimentation rate studies of rat liver microsomes led previously to the assignment of microsomal constituents into group a1 (monoamine oxidase), group a2 (5'-nucleotidase, alkaline phosphodiesterase I, alkaline phosphatase and cholesterol), group a3 (galactosyltransferase), group b (NADH cytochrome c reductase, NADPH cytochrome c reductase, aminopyrine demethylase, cytochrome b(5) and P 450), and group c (glucose 6-phosphatase, esterase, nucleoside diphosphatase, beta-glucuronidase and glucuronyltransferase). Confirmation and extension of the assignment into groups has been obtained by studying the differential effect of the reagents digitonin, EDTA, and PPi. Digitonin specifically affected the equilibrium density only of the group a2 and (to a lesser extent) group a3, and not of groups b and c under conditions which preserved the structure-linked latency of nucleoside diphosphatase and galactosyltransferase. Within experimental error the rate of sedimentation of all microsomal constituents was unaffected. The morphological appearance under the electron microscope was indistinguishable from that of nondigitonin-treated microsomes, except that a few smooth membranes (< 10%) exhibited broken-looking profiles. Treatment of microsomes with EDTA or PPi detached a substantial part of RNA and released protein in excess over the amount accountable for by detachment of ribosome constituents. This detachment was confirmed by electron microscopy. EDTA and PPi decreased markedly the equilibrium density and the density dispersion of groups b and c, due mainly to the uncoating of rough elements. EDTA and PPi shifted slightly the distribution profiles of groups a towards lower densities, possibly as a result of the release of adsorbed proteins. The combination of EDTA and digitonin, used subsequently, rendered the average equilibrium density of group a2 higher than that of groups b and c. Dense subfractions were thus enriched in constituents of group a2 and showed mainly broken-looking vesicles under the electron microscope. The import of our results on the biochemical and enzymic properties of the subcellular components of the microsome fractions is discussed.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver. IV. Biochemical, physical, and morphological modifications of microsomal components induced by digitonin, EDTA, and pyrophosphate. 436 10

Pyrophosphate, p-nitrophenyl phosphate and a variety of pyrimidine and purine nucleotides are hydrolyzed by the solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. The pH optima (or ranges) for hydrolysis of substrates are 8.0 (pyrophosphate), 8.8 (p-nitrophenyl phosphate), 8.4-8.9 (nucleoside monophosphates), and 7.1-8.1 (nucleoside triphosphates); all substrates, with the exception of nucleoside triphosphates, have a higher affinity for the solubilized enzyme at pH 7.4 than at their optimal pH for hydrolysis. ATP is degraded completely by the enzyme preparation to adenosine and inorganic phosphate, but since neither ADP nor ATP accumulate in the incubation medium it is not known whether ATP hydrolysis involves the sequential hydrolysis of terminal phosphate groups. Isoelectric focusing and various chromatographic procedures (gel permeation, ion-exchange and hydrophobic interaction chromatography) fail to separate the alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities associated with the solubilized membrane preparation. Additionally, inhibitor studies indicate that only a single enzyme with low substrate specificity is involved in the hydrolysis of nucleotides, p-nitrophenyl phosphate, pyrophosphate and hexose phosphate esters. Purines and pyrimidines and their nucleosides interact with the active site, and in some instances activity of the enzyme is stimulated by an unknown mechanism.
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PMID:Nucleotide hydrolysis by solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. 613 88

Membrane-bound extracellular matrix vesicles play an important role in the de novo initiation and propagation of calcium-phosphate mineral formation in calcifying cartilage, bone, dentin, and in pathologic calcification. Characterization of the phase, composition, crystal size, and perfection provides valuable insight into the mechanism of the mineral deposition. In the present study, Fourier transform infrared imaging spectroscopy (FT-IRIS) was used to characterize the mineral phase generated during MV-mediated in vitro mineralization. FT-IRIS studies revealed that the mineral phase associated with MVs calcified in the presence of AMP and beta-GP was always found to be crystalline hydroxyapatite while with ATP only a small amount of immature mineral, most likely an amorphous or poorly crystalline hydroxyapatite, was observed. Low concentrations of pyrophosphate (PPi) (< or = 0.01 mM) showed apatitic mineral while high concentrations showed immature calcium pyrophosphate dihydrate (CPPD). The implications of these findings are that (a) hydrolysis of AMP or beta-GP, monophosphoester substrates of MV-5' AMPase (substrate: AMP) and TNAP (substrates: AMP, beta-GP), yields orthophosphate (Pi) which leads to the formation of mature crystalline, apatite mineral, while the hydrolysis of ATP, substrate for MV-TNAP or ATPase or NPP1, inhibits the formation of mature hydroxyapatite, and (b) pyrophosphate (PPi) has a bimodal effect on mineralization, i.e., at low PPi concentrations, alkaline phosphatase activity of matrix vesicles is able to hydrolyze PPi to orthophosphate and thus facilitates the formation of basic calcium phosphate mineral which subsequently transforms into apatitic mineral. We hypothesize that, at high PPi concentrations, PPi by itself or Pi released by partial PPi hydrolysis could act as inhibitors of alkaline phosphatase activity, thereby preventing complete hydrolysis of PPi to Pi, and thus resulting in the accumulation of calcium pyrophosphate dihydrate. Therefore, in order for physiological mineralization to proceed, a balance is required between levels of Pi and PPi.
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PMID:Nature of phosphate substrate as a major determinant of mineral type formed in matrix vesicle-mediated in vitro mineralization: An FTIR imaging study. 1646 Oct 32

Among the myriad of enzymes present in animal venoms, nucleotidases and nucleases are poorly investigated. Herein, we studied such enzymes in 28 crude venoms of animals found in Brazil. Higher levels of ATPase, 5'-nucleotidase, ADPase, phosphodiesterase and DNase activities were observed in snake venoms belonging to Bothrops, Crotalus and Lachesis genera than to Micrurus genus. The venom of Bothrops brazili snake showed the highest nucleotidase and DNase activities, whereas that of Micrurus frontalis snake the highest alkaline phosphatase activity. On the other hand, the venoms of the snake Philodryas olfersii and the spider Loxosceles gaucho were devoid of most nucleotidase and DNase activities. Species that exhibited similar nucleotidase activities by colorimetric assays showed different banding pattern by zymography, suggesting the occurrence of structural differences among them. Hydrolysis of nucleotides showed that 1 mol of ATP is cleaved in 1 mol of pyrophosphate and 1 mol of orthophosphate, whereas 1 mol of ADP is cleaved exclusively in 2 mol of orthophosphates. Pyrophosphate is barely hydrolyzed by snake venoms. Phosphodiesterase activity was better correlated with 5'-nucleotidase, ADPase and ATPase activities than with DNase activity, evidencing that phosphodiesterases are not the main agent of DNA hydrolysis in animal venoms. The omnipresence of nucleotidase and DNase activities in viperid venoms implies a role for them within the repertoire of enzymes involved in immobilization and death of preys.
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PMID:Nucleotidase and DNase activities in Brazilian snake venoms. 1790 25

A variety of extreme environments, characterized by extreme values of various physicochemical parameters (temperature, pressure, salinity, pH, and so on), are found on Earth. Organisms that favorably live in such extreme environments are called extremophiles. All living organisms, including extremophiles, must acquire energy to maintain cellular homeostasis, including extremophiles. For energy conversion in harsh environments, thermodynamically useful reactions and stable biomolecules are essential. In this review, I briefly summarize recent studies of extreme environments and extremophiles living in these environments and describe energy conversion processes in various extremophiles based on my previous research. Furthermore, I discuss the correlation between the biological system of electrotrophy, a third biological energy acquisition system, and the mechanism underlying microbiologically influenced corrosion. These insights into energy conversion in extremophiles may improve our understanding of the "limits of life". Abbreviations: PPi: pyrophosphate; PPase: pyrophosphatase; ITC: isothermal titration microcalorimetry; SVNTase: Shewanella violacea 5'-nucleotidase; SANTase: Shewanella amazonensis 5'-nucleotidase.
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PMID:Biochemical and thermodynamic analyses of energy conversion in extremophiles. 3038 Oct 12