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

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

Sixteen isolates of Mycoplasma ovipneumoniae recovered from the nasal tract or lungs of sheep from different flocks in New Zealand were examined by bacterial restriction endonuclease DNA analysis (BRENDA) using EcoR1 and by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). All isolates gave BRENDA patterns which differed entirely from one another. Following 20 serial passages (corresponding to approximately 67 generations) of an isolate, no change was detected in the BRENDA pattern. When eight isolates were examined by SDS-PAGE most bands were common but, nevertheless, each isolate was unique in the sense that they differed from one another in one or more bands. The marked heterogeneity of patterns observed when strains of M. ovipneumoniae are compared by BRENDA, together with the stability of such patterns over many generations, will enable this approach to be used to study the epidemiology of individual strains of M. ovipneumoniae within a flock.
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PMID:Comparison of Mycoplasma ovipneumoniae isolates using bacterial restriction endonuclease DNA analysis and SDS-PAGE. 300 24

The nrdB gene of Escherichia coli, coding for the B2 protein of ribonucleotide reductase, has been cloned in a runaway-replication vector. The runaway derivative pBEU17 carries the promoter-proximal portion of the E. coli alanyl-tRNA synthetase gene and proved useful for expressing cloned genes lacking their native transcription initiation signals. The alaS promoter is located approximately 500 base pairs upstream of a single BamHI restriction endonuclease cleavage site utilized in the construction of an expression recombinant plasmid, pBS1, for the nrdB product. After 5-h thermal induction of cells carrying the runaway recombinant pBS1, protein B2 constituted 40% of the soluble protein fraction of the cells. The high concentration of protein B2 in crude extracts of induced cells has enabled a simplified purification scheme to be developed for production of homogeneous and concentrated B2 preparations. Protein B2 produced from pBS1 is identical to the chromosomally encoded nrdB product of E. coli as regards molecular mass on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme activity, tyrosine radical content, and structure of the binuclear iron center. Amino acid sequence analysis showed that the two polypeptide chains of protein B2 are identical. They start with an alanine residue, and the first 30 residues confirmed the amino acid sequence predicted from the nucleotide sequence of the nrdB gene, apart from an NH2-terminal processing removal of the initiator methionine.
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PMID:Overproduction and purification of the B2 subunit of ribonucleotide reductase from Escherichia coli. 300 19

The restriction endonuclease Alu I induces chromosomal aberrations and mutations in the hypoxanthine phosphoribosyltransferase (HPRT) locus as measured by 6-thioguanine resistance (TGr) in V79 hamster cells. Alu I does not induce mutations in the Na+/K+ ATPase locus as measured by ouabain resistance (OUAr). The data are interpreted to mean that most if not all Alu I-induced TGr mutations represent chromosomal aberrations.
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PMID:The restriction endonuclease Alu I induces chromosomal aberrations and mutations in the hypoxanthine phosphoribosyltransferase locus, but not in the Na+/K+ ATPase locus in V79 hamster cells. 301 99

Nucleases derived from Neurospora crassa mycelia with neutral single-strand (ss) endodeoxyribonuclease activity have been examined by immunochemical techniques and by sodium dodecyl sulfate - DNA gel electrophoresis. All of the intracellular nucleases, which have different divalent metal ion requirements, different strand specificities with single- and double-strand DNA, different modes of action on DNA and RNA, and other distinguishing characteristics, are immunochemically related to Neurospora endo-exonuclease. The evidence indicates that these enzymes are derived from one or more related large, inactive (precursor?) polypeptides that are first converted to 75- to 80-kdalton active polypeptide(s) which are very protease sensitive. Further limited proteolysis results in the production of the various active forms of nuclease studied here. Some proteolytic conversions may occur in a controlled manner in vivo in different cell compartments, but others are very likely artifacts resulting from uncontrolled proteolysis during extraction and isolation. The intracellular forms of Neurospora endo-exonuclease are immunologically cross-active with ss-DNA-binding nucleases isolated from Aspergillus nidulans and Saccharomyces cerevisiae. They are not immunochemically related to two extracellular Neurospora nucleases, the pancreatic DNase-I-like DNase A and a ss-specific exonuclease, and they are also not related to other fungal and plant nucleases with ss-specific endonuclease activity such as the S1 nuclease of Aspergillus oryzae, the P1 nuclease of Penicillium citrinum, and mung bean nuclease.
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PMID:An immunochemical study of Neurospora nucleases. 301 42

The technique of localized in vitro mutagenesis in the cohesive ends of plasmid pBR322 DNA has been elaborated (separately for BamHI and HindIII sites). Plasmid DNA digested by restriction endonucleases has been treated with sodium bisulphite deaminating cytosine to form uracil in single stranded DNA (cohesive ends of the plasmid). The mutagenized plasmid DNA, free of mutagen, has been treated with bacteriophage T4 ligase. E. coli C600 cells were subsequently transformed by the ligated DNA preparation. The clones having tetracycline gene mutagenized represented 4.0-11.1% and 1.2-3.1% among HindIII and BamHI mutants, respectively, selected as TcR----TcS transformants. Selection of mutagenized DNA by the second endonuclease restriction has increased the mutant yields up to 55.6-78.0% and 10.0-75.4%, respectively. The yield of TcS mutations in the control DNA treated at all stages of experiment, except for mutagen treatment, has reached 0.06% and 0.2%, respectively.
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PMID:[Localized mutagenesis of the tetracycline gene in the plasmid pBR322 induced by sodium bisulfite in vitro]. 302 19

To determine whether multiple forms of the Na+,K+-ATPase beta subunit exist in rat kidney and brain, we constructed cDNA libraries from both tissues and isolated clones carrying inserts coding for this subunit. Characterization of these cDNAs by restriction endonuclease mapping and DNA sequencing suggests that a single form of the beta subunit protein is present in these tissues. We did, however, find that the beta subunit was encoded by multiple mRNAs which can be grouped into classes based on the lengths of their 5' and 3' untranslated regions. Size variation at the 3' end is due to the use of at least two of the five potential polyadenylation sites, whereas variation at the 5' end appears to be due to the use of different initiation sites. Northern blot analysis demonstrates the presence of multiple mRNA species which correlate with the sizes observed for the different cDNA classes and also demonstrates that the larger mRNA species are present at different levels in kidney and brain. S1 and primer extension analyses suggest that the observed tissue differences in the expression of these mRNAs are due to transcription from multiple initiation sites, whose strength is tissue-dependent. In the 3' untranslated region, comparison of the nucleotide sequence of the rat beta subunit cDNAs to those from other species reveals regions of high sequence similarity.
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PMID:Multiple mRNAs from rat kidney and brain encode a single Na+,K+-ATPase beta subunit protein. 303 Oct 33

Brazilian purpuric fever (BPF) is a recently recognized fulminant pediatric disease characterized by fever, with rapid progression to purpura, hypotensive shock, and death. BPF is usually preceded by purulent conjunctivitis that has resolved before the onset of fever. Both the conjunctivitis and BPF are caused by Haemophilus influenzae biogroup aegyptius (formerly called H. aegyptius). Isolates from 15 BPF cases, mainly from blood or hemorrhagic cerebrospinal fluid, case-associated isolates from 42 persons in towns where BPF cases occurred, and control strains from 32 persons in towns without BPF cases were characterized biochemically, genetically, and epidemiologically. Results indicated that a single clone was responsible for all BPF cases identified in six Brazilian towns from 1984 through 1986. All of 15 (100%) case strains were the same clone as was 1 of 32 (3%) control strains (P = less than 10(-8). Isolates of the clone were preferentially intrarelated by DNA hybridization (99% relatedness, hydroxyapatite method at 60 and 75 degrees C) and were separable from other H. influenzae biogroup aegyptius strains (approximately 90% relatedness at 60 degrees C and 82% relatedness at 75 degrees C). All isolates of the BPF clone and no other strains contained a 24-megadalton plasmid of restriction endonuclease type 3031, were of a single multilocus enzyme mobility type, were of a single sodium dodecyl sulfate-polyacrylamide gel electrophoresis type, and were in one of two ribosomal DNA restriction patterns. All BPF clone isolates reacted with monoclonal antibodies produced from a case strain; only 3 of 62 (5%) other strains reacted with this monoclonal antibody. Ninety percent of BPF clone strains and 27% of other strains were relatively resistant to sulfamethoxazole-trimethoprim.
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PMID:Biochemical, genetic, and epidemiologic characterization of Haemophilus influenzae biogroup aegyptius (Haemophilus aegyptius) strains associated with Brazilian purpuric fever. 326 23

A cDNA library was constructed using poly(A) +RNA from bovine mammary gland. This cDNA library of 6000 clones was screened employing colony hybridization using 32P-labelled oligonucleotide probes and restriction endonuclease mapping. The cDNA from the selected plasmid, pKR76, was sequenced using the dideoxy-chain termination method. The cDNA insert of pKR76 carries the full-length sequence, which codes for mature kappa-casein protein. The amino acid sequence deduced from the cDNA sequence fits the published amino acid sequence with three exceptions; the reported pyroglutamic acid at position 1, tyrosine at position 35, and aspartic acid at position 81 are, respectively, a glutamine, a histidine, and an asparagine in the clone containing pKR76. The MspI-, NlaIV-cleaved fragment (630 base pair) from the kappa-casein cDNA insert has been subcloned into expression vectors pUC18 and pKK233-2, which contain a lac promoter and a trc promoter, respectively. Escherichia coli cells carrying the recombinant expression plasmids were shown to produce kappa-casein protein having the expected mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and being recognized by specific antibodies raised against natural bovine kappa-casein.
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PMID:Molecular cloning and expression of bovine kappa-casein in Escherichia coli. 328 96

Binding interactions between the membrane-associated vitamin K-dependent carboxylase and its prothrombin and factor X substrates have been investigated in liver microsomes. Both substrates are firmly attached to microsomal membrane fragments which also harbor the carboxylase. In vitro 14CO2 gamma-carboxylation of these substrates, triggered by reduced vitamin K1H2, resulted in release of 14C-labeled prothrombin precursors from the membrane fragments, but no release of 14C-labeled factor X precursors could be demonstrated, which suggested a difference in early processing of these substrates by the carboxylase. Warfarin treatment of rats resulted in a 3-fold increase in the membrane concentration of factor X antigens and a 20-fold increase in 14C gamma-carboxylation of the membrane pool of factor X carboxylase substrates. There was a dose-response relationship between the amount of drug administered to the rats and 14C labeling of the membrane pool of factor X carboxylase substrates. On the other hand, the membrane concentration of prothrombin antigens did not increase in response to the drug, and 14CO2 gamma-carboxylation of the membrane pool of prothrombin carboxylase substrates was the same in warfarin and saline-treated rats. The results demonstrate significant differences in the interaction between the carboxylase and its prothrombin and factor X substrates. It appears that the different interactions result from binding of the prothrombin and the factor X precursors to separate microsomal membrane proteins that are involved in the gamma-carboxylation reaction. Warfarin appears to induce the factor X precursor-specific but not the prothrombin precursor-specific binding proteins, which suggests a new mechanism for the action of warfarin. These binding proteins may be under different genetic control. Treatment of the prothrombin and the factor X carboxylase substrates with endonuclease H showed that the rat prothrombin and the human factor X carboxylase substrates are high mannose glycoproteins. The human prothrombin and the rat factor X carboxylase substrates did not, on the other hand, change their migration in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after endonuclease H treatment. The data demonstrate differences in the glycoprotein nature of the rat and the human carboxylase substrates.
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PMID:Early processing of prothrombin and factor X by the vitamin K-dependent carboxylase. 329 Feb 18

The kinetics of protein-nucleic acid interactions are discussed with particular emphasis on the effects of salt concentration and valence on the observed rate constants. A general review is given of the use of experimentally determined salt dependences of observed kinetic parameters as a tool to probe the mechanism of interaction. Quantitative analysis of these salt dependences, through the application of polyelectrolyte theory, can be used to distinguish reactions which occur in a single step from those reactions which involve distinct intermediates. For those rate constants which display a large salt dependence, in either the association or dissociation reaction, this is due to the high concentration of counterions (e.g., Na+) in the vicinity of the nucleic acid which are subsequently released (or bound in the case of dissociation) at some point before the rate limiting step of the reaction. A general discussion of other features which affect protein-nucleic acid kinetics, such as nucleic acid length and the ratio of nonspecific to specific DNA binding sites (in the case of sequence specific binding proteins), is also given. The available data on the nucleic acid binding kinetics of small ligands (ions, dyes, oligopeptides), nonspecific binding proteins (T4 gene 32 protein, fd gene 5 and Escherichia coli SSB), and sequence specific binding proteins (lac repressor, RNA polymerase, Eco RI restriction endonuclease) are discussed with emphasis on the interpretation of the experimentally determined salt dependences.
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PMID:Kinetics of protein-nucleic acid interactions: use of salt effects to probe mechanisms of interaction. 351 64


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