Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

51 methane-oxidizing bacteria strains such as Methylomonas methanica, M. rubra, Methylococcus capsulatus, M. thermophilus, M. luteus, M. ucrainicus, M. whittenburyi, Methylosinus trichosporium, M. sporium, Methylocystis parvus isolated from various ecological niches and geographical regions of the Ukraine and also the strains received from R. Whittenbury and Y. Heyer were screened for restriction endonucleases. Type II restriction endonucleases were detected in IMV B-3112 (= 12 b), IMV B-3027 (= 26), IMV B-3019 (= 9 c), IMV B-3017 (= 17 c), IMV B-3226 (= 26 v), IMV B-3033 (= Y), IMV B-3100 (= 100) and IMV B-3494 (= 1E494). The results obtained were indicative of relatively high frequency of restriction enzymes occurrence in methane-oxidizing bacteria. There were Kpn I (Asp 7181) restriction endonuclease isoschizomers in crude extracts of IMV B-3112, B-3017, B-3019, B-3027 isolated from fresh-water silt as well as in IMV B-3226 strain isolated from waste-water silt. Although these isolates had bee previously considered as untypical strains of M. ucrainicus, more detailed study of their properties allowed placing them with Methylovarius luteus (= Methylococcus luteus). IMV B-3494 strain was identified as Methylococcus capsulatus. Strain IMV B-3033 had earlier been allocated to Methylovarius whittenburyi (= Methylococcus whittenburyi). Specificity of restriction endonucleases of this strain was not tested. Therefore, for the first time restriction endonucleases were detected in methane-oxidizing bacteria. 8 strains (3 species) among 51 strains (13 species) were found to produce restriction endonucleases displaying three different types of specificity in the least. Producers of restriction endonucleases having Kpn I (Asp 7181) specificity were isolated from different water and silt samples of the Dnieper flood-land more than 20 years ago.
...
PMID:Screening for restriction endonucleases in methane-oxidizing bacteria. 133 16

Streptococcus mutans GS5 expresses three glucosyltransferases (GTFs): GTF-I and GTF-SI, which synthesize water-insoluble glucans in a primer-independent manner, and GTF-S, which is responsible for the formation of primer-dependent soluble glucan. The amino acid sequences of the GTF-I and GTF-S enzymes exhibit approximately 50% sequence identity. Various hybrid genes were constructed from the structural genes for the enzymes, and their products were analyzed. Three different approaches were used to construct the hybrid enzymes: (i) ligation of DNA fragments containing compatible endonuclease restriction sites of the two genes at homologous positions; (ii) in vivo recombination between the homologous regions of each gene; and (iii) random fusion of DNA fragments from each gene generated following exonuclease III digestion of tandemly arranged fragments corresponding to the two functional domains of each enzyme. Hybrid GTFs composed of the sucrose-binding domain of one enzyme (GTF-I or GTF-S) with the glucan-binding domain of the other synthesized insoluble glucan exclusively in the absence of primer dextran. Insoluble glucan synthesis by some, but not all, of the GTF-S:GTF-I chimeric enzymes was stimulated by primer dextran T10 addition. In addition, glucan binding by the former but not latter group of hybrid GTFs was demonstrated. These results suggest that the glucan-binding domain alone does not solely determine primer dependence or independence or the structure of the resulting glucan product, although this carboxyl-terminal domain containing direct repeating units does appear to play a significant role in primer dependence.
...
PMID:Mechanism of Streptococcus mutans glucosyltransferases: hybrid-enzyme analysis. 138 95

A patient undergoing esophageal dilatation for carcinoma of the esophagus suffered esophageal perforation and development of an empyema. Culture of pleural fluid yielded multiple organisms, including Legionella pneumophila serogroup 5. Epidemiologic investigation showed that the source of L pneumophila was a tap used by the nursing personnel to fill patients' water pitchers. Whole-cell restriction endonuclease analysis of DNA from the clinical and environmental isolates of L pneumophila serogroup 5 yielded identical patterns. Our findings suggest that L pneumophila was acquired by the patient at least 12 h prior to the procedure causing the esophageal perforation and empyema, suggesting that the organism can persist in an infectious form in the upper aerodigestive tract.
...
PMID:Isolation of Legionella pneumophila serogroup 5 from empyema following esophageal perforation. Source of the organism and mode of transmission. 142 1

Enterococcus faecalis 226 NWC, isolated from natural whey cultures utilized as starter in water-buffalo Mozzarella cheese manufacture, produces a bacteriocin, designated Enterocin 226 NWC, which is inhibitory to Listeria monocytogenes. Plasmid analysis of E. faecalis 226 NWC showed a single 5.2-kb plasmid, pEF226. In conjugation experiments, pEF226 was transferred into a plasmid-free strain of E. faecalis JH2-2. The transfer required direct cell-to-cell contact and was not inhibited by DNase. The identity of conjugation was confirmed by digestion with SmaI restriction endonuclease and subsequent pulsed-field gel electrophoresis (PFGE) of the genomic DNA of E. faecalis 226, E. faecalis JH2-2 and of the isolates after the mating. The data indicate that the ability of E. faecalis 226 NWC to produce the bacteriocin is linked to the 5.2-kb conjugative plasmid pEF226.
...
PMID:Conjugal transfer of plasmid-borne bacteriocin production in Enterococcus faecalis 226 NWC. 146 12

O6-Alkylguanine-DNA alkyltransferase (ATase) activity was determined in crude sonicates of tissues obtained from the F2 offspring of human ATase transgenic founder mice. In certain cases, samples were analyzed both before and after administration of zinc sulfate in the drinking water for 2 wk to upregulate the mouse metallothionein-1 promoter that controls the expression of the transgene. In liver samples obtained by partial hepatectomy, the ATase activities of nontransgenic mice ranged from 63 to 139 fmol/mg total protein (mean of 10 mice, 95.3 +/- 23 fmol/mg), whereas in positive transgenic mice, the range was from 503 to 2119 fmol/mg (mean of 10 mice, 963 +/- 475 fmol/mg). The difference between the mean ATase values for these two groups of mice is highly significant (P less than 0.001). All positive mice expressed ATase and in those examined using the human ATase coding sequence as a probe, isoschizomeric-restriction endonuclease digestion showed no evidence of cytosine methylation in the transgene. After zinc sulfate induction, the ATase levels in residual liver tissue were for the controls 84-191 fmol/mg (mean of 10 mice, 123 +/- 31.5 fmol/mg) and for positive mice 908-3273 fmol/mg (mean of 10 mice, 1960 +/- 724 fmol/mg). Induction thus caused a 1.4- to 3.2-fold increase in ATase activity in the tissues of individual transgenic mice (mean, 1.8-fold; P less than 0.003), with the greatest increase generally occurring in those mice that had the lowest preinduction levels. Hepatic ATase levels were thus increased up to 28 times higher in transgenic mice than in nontransgenic mice. When data from other groups of transgenic and nontransgenic mice (eight of each) was included and analyzed in an independent rather than paired fashion, the mean values for zinc-treated controls and transgenic mice, respectively, were 106 fmol/mg and 1415 fmol/mg, still a highly significant (P less than 0.001) difference. In two mice given a single intraperitoneal dose of cadmium chloride, hepatic ATase increased 2.1- and 4.9-fold, respectively. The effect of partial hepatectomy alone was also considered: for transgenic mice the mean ATase level increased from 453 to 661 fmol/mg protein after 48 h. In other offspring subjected to either unilateral nephrectomy or orchidectomy, induction of ATase activity by zinc sulfate was also seen in kidney (5.7- and 8.4-fold) and testis (1.7- and 3.1-fold), although these observations were made with small numbers of mice.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Tissue-specific expression and induction of human O6-alkylguanine-DNA alkyltransferase in transgenic mice. 150 42

The stereochemical course of the reaction catalyzed by the EcoRV restriction endonuclease has been determined. This endonuclease recognizes GATATC sequence and cuts between the central T and dA bases. The Rp isomer of d(GACGATsATCGTC) (this dodecamer contains a phosphorothioate rather than the usual phosphate group between the central T and dA residues, indicated by the s) was a substrate for the endonuclease. Performing this reaction in H2 18O gave [18O]dps(ATCGTC) (a pentamer containing an 18O-labeled 5'-phosphorothioate) which was converted to [18O]dAMPS with nuclease P1. This deoxynucleoside 5'-[18O]phosphorothioate was stereospecifically converted to [18O]dATP alpha S with adenylate kinase and pyruvate kinase [Brody, R. S., & Frey, P. A. (1981) Biochemistry 20, 1245-1251]. Analysis of the position of the 18O in this product by 31P NMR spectroscopy showed that it was in a bridging position between the alpha- and beta-phosphorus atoms. This indicates that the EcoRV hydrolysis proceeds with inversion of configuration at phosphorus. The simplest interpretation is that the mechanism of this endonuclease involves a direct in-line attack at phosphorus by H2O with a trigonal bipyramidal transition state. A covalent enzyme oligodeoxynucleotide species can be discounted as an intermediate. An identical result has been previously observed with the EcoR1 endonuclease [Connolly, B. A., Eckstein, F., & Pingoud, A. (1984) J. Biol. Chem. 259, 10760-10763]. X-ray crystallography has shown that both of these endonucleases contain a conserved array of amino acids at their active sites. Possible mechanistic roles for these conserved amino acids in the light of the stereochemical findings are discussed.
...
PMID:Stereochemical outcome of the hydrolysis reaction catalyzed by the EcoRV restriction endonuclease. 151 Sep 72

Alkaline phosphatase was the first zinc enzyme to be discovered in which three closely spaced metal ions (two Zn ions and one Mg ion) are present at the active center. Zn ions at all three sites also produce a maximally active enzyme. These metal ions have center-to-center distances of 3.9 A (Zn1-Zn2), 4.9 A (Zn2-Mg3), and 7.1 A (Zn1-Mg3). Despite the close packing of these metal centers, only one bridging ligand, the carboxyl of Asp51, bridges Zn2 and Mg3. A crystal structure at 2.0-A resolution of the noncovalent phosphate complex, E.P, formed with the active center shows that two phosphate oxygens form a phosphate bridge between Zn1 and Zn2, while the two other phosphate oxygens form hydrogen bonds with the guanidium group of Arg166. This places Ser102, the residue known to be phosphorylated during phosphate hydrolysis, in the required apical position to initiate a nucleophilic attack on the phosphorous. Extrapolation of the E.P structure to the enzyme-substrate complex, E.ROPO4(2-), leads to the conclusion that Zn1 must coordinate the ester oxygen, thus activating the leaving group in the phosphorylation of Ser102. Likewise, Zn2 appears to coordinate the ester oxygen of the seryl phosphate and activate the leaving group during the hydrolysis of the phosphoseryl intermediate. Both of these findings suggest that there may be a significant dissociative character to each of the two displacements at phosphorous catalyzed by alkaline phosphatase. A water molecule (or hydroxide) coordinated to Zn1 following formation of the phosphoseryl intermediate appears to be the nucleophile in the second step of the mechanism. Dissociation of the product phosphate from the E.P intermediate is the slowest, 35 s-1, and therefore the rate-limiting, step of the mechanism at alkaline pH. Since the determination of the initial crystal structure of alkaline phosphatase, two other crystal structures of enzymes involved in phosphate ester hydrolysis have been completed that show a triad of closely spaced zinc ions present at their active centers. These enzymes are phospholipase C from Bacillus cereus (structure at 1.5-A resolution) (43) and P1 nuclease from Penicillium citrinum (structure at 2.8-A resolution) (74). Both enzymes hydrolyze phosphodiesters. Substrates for phospholipase C are phosphatidylinositol and phosphatidylcholine, while P1 nuclease is an endonuclease hydrolyzing single stranded ribo- and deoxyribonucleotides. P1 nuclease also has activity as a phosphomonoesterase against 3'-terminal phosphates of nucleotides. The Zn ions in both enzymes form almost identical trinuclear sites.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Structure and mechanism of alkaline phosphatase. 152 73

We report the case of a 70-year-old man who was admitted to hospital A 66 days before developing Legionella pneumophila pneumonia 6 days after open heart surgery at hospital C. The strain of L. pneumophila recovered from the patient's sputum was of the same subtype (monoclonal antibody type, enzyme type, plasmid profile, and restriction endonuclease pattern) as a strain of L. pneumophila in the potable water supplied to the room where he stayed in hospital A. We conclude that the patient's respiratory tract became colonised by L. pneumophila while he was in hospital A and persisted for at least 63 days until he developed pneumonia requiring antibiotic treatment while in hospital C.
...
PMID:Colonisation of the respiratory tract with Legionella pneumophila for 63 days before the onset of pneumonia. 154 22

Whole cell DNA of Legionella pneumophila isolates was examined by small-fragment restriction endonuclease analysis (SF-REA). Fourteen serogroup 1 isolates from tap water in one hospital collected before and after eradication measures had been taken were compared with control strains of serogroup 1 and other serogroups that were not epidemiologically linked. DNA was digested with EcoRI and electrophoresed on polyacrylamide gels. The gel patterns were made visible by silver staining and analysed by direct visual comparison. All 15 epidemiologically unrelated strains of Legionella pneumophila serogroup 1 and of other serogroups exhibited different restriction fragment patterns. The isolates from the hospital could be clearly subdivided into two groups by SF-REA, suggesting that the hot water supply of the hospital was contaminated with two different strains. SF-REA performed on Legionella pneumophila serogroup 1 DNA enabled further subtyping of these organisms and thus appears to be a useful technique for investigating their epidemiology.
...
PMID:Subtyping of Legionella pneumophila serogroup 1 isolates by small-fragment restriction endonuclease analysis. 174 16

Approximately 1 year after purchase of one manufacturer's automated endoscope washing machine, we began to detect heavy contamination of upper gastrointestinal (UGI) endoscopes cultured after cleaning and disinfection in the washer. During the first 6 months of 1988, 77% of surveillance cultures (20-mL flush through the biopsy channel) were positive for gram-negative bacilli (median concentration, 10(5) cfu/mL), most frequently Pseudomonas aeruginosa serotype 10. During the first 19 months of use of the washer, nosocomial post-UGI endoscopy colonization or infections with P. aeruginosa increased 36%. Investigations show that endoscope contamination derives from a flaw in the design of the EW-10 washer: the detergent holding tank, inlet water hose, and air vents cannot be reliably disinfected and contain heavy biofilms that recontaminate the machine after it has been disinfected, as specified by the manufacturer, with glutaraldehyde. Only by rinsing machine-cleansed endoscopes with 70% alcohol followed by forced air drying has reliable disinfection been achieved. Since adaptation of terminal alcohol treatment and drying, post-UGI endoscopy colonization or infection by P. aeruginosa has declined threefold (p less than 0.001). Testing in other centers using the manufacturer's EW-10 or EW-20 washer has shown similar contamination. In three centers, including our own, postendoscopy infections by machine-associated type 10 P. aeruginosa have been confirmed by demonstrating concordance between isolates from contaminated machines or endoscopes and from infected patients by immunoblot of whole cell lysates and by pulsed-field electrophoresis of DraI endonuclease-digested genomic DNA. This problem reaffirms the vulnerability to microbial contamination of water-containing apparatus and equipment in patient care and points up the critical importance of engineering design to prevent contamination.
...
PMID:Nosocomial infections from contaminated endoscopes: a flawed automated endoscope washer. An investigation using molecular epidemiology. 192 77


1 2 3 4 5 6 7 8 9 10 Next >>

---