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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Double-stranded DNA fragments of different length with and without the incorporation of 7-deazapurine deoxynucleotides have been prepared via the polymerase chain reaction (PCR) using exo(-)Pseudococcus furiosus DNA polymerase, unmodified primers, and c7-dATP and c7-dGTP as the only purine triphosphates. In spite of the presence of some unmodified purine moieties due to the primers, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry revealed remarkable differences between the modified and unmodified DNA fragments. The incorporation of 7-deazapurine nucleotides resulted in a significant reduction of fragmentation and therefore in increased signal intensities and higher mass resolution. The molecular weights could be determined with an accuracy of up to 0.03%. Mass resolution was sufficient to resolve the (M + H)+ signals of the two single strands of a 7-deazapurine-containing 99-base-pair DNA duplex. Thus, MALDI-TOF mass spectrometry offers a very fast and accurate way to detect and analyze short PCR products sufficient in length for many diagnostic applications without gel electrophoresis and labeling.
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PMID:Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the detection of polymerase chain reaction products containing 7-deazapurine moieties. 895 25

We report a simple method, the PinPoint assay, for detecting and identifying single-base variations (polymorphisms) at specific locations within DNA sequences. An oligonucleotide primer is annealed to the target DNA immediately upstream of the polymorphic site and is extended by a single base in the presence of all four dideoxynucleotide triphosphates and a thermostable DNA polymerase. The extension products are desalted, concentrated, and subjected to delayed-extraction MALDI-TOF mass spectrometry. The base at the polymorphic site is identified by the mass added onto the primer. Heterozygous targets produce two mass-resolved species that represent the addition of both bases complementary to those at the polymorphic site. The assay is suitable for double-stranded PCR products without purification or strand separation. More than one primer can be simultaneously extended and then mass-analyzed. The mass spectrometric method thus shows promise for high-volume diagnostic or genotyping applications.
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PMID:Single-nucleotide polymorphism identification assays using a thermostable DNA polymerase and delayed extraction MALDI-TOF mass spectrometry. 911 Jan 77

1-(2-Deoxy-beta-D-erythro-pentofuranosyl)cyanuric acid (cyanuric acid nucleoside, dY) (1) has been shown to be formed upon exposure of DNA components to ionizing radiation and excited photosensitizers. To investigate the biological and structural significance of dY residue in DNA, the latter modified 2'-deoxynucleoside was chemically prepared and then site-specifically incorporated into oligodeoxyribonucleotides (ODNs). This was achieved in good yields using the phosphoramidite approach. For this purpose, a convenient glycosylation method involving 3,5-protected 2-deoxyribofuranoside chloride and cyanuric acid (2,4,6-trihydroxy-1,3,5-triazine) was devised. The anomeric mixture of modified 2'-deoxyribonucleosides (1/2 alpha/beta) was resolved by silica gel purification of the 5'-O-dimethoxytritylated derivatives, and then, phosphitylation afforded the desired beta-phosphoramidite monomer (5). After solid-phase condensation and final deprotection, the purity and the integrity of the modified synthetic DNA fragments were checked using different complementary techniques such as HPLC and polyacrylamide gel electrophoresis, together with electrospray ionization and MALDI-TOF mass spectrometry. The presence of cyanuric acid nucleoside in a 14-mer was found to have destabilizing effects on the double-stranded DNA fragment as inferred from melting temperature measurements. The piperidine test applied to dY-containing ODNs supported the high stability of cyanuric acid nucleoside inserted into the oligonucleotide chain. Several enzymatic experiments aimed at determining the biological features of such a DNA lesion were carried out. Thus, processing of dY by nuclease P(1), snake venom phosphodiesterase (SVPDE), calf spleen phosphodiesterase (CSPDE), and repair enzymes, including Escherichia coli endonuclease III (endo III) and Fapy glycosylase (Fpg), was investigated. Finally, a 22-mer ODN bearing a cyanuric acid residue was used as a template to study the in vitro nucleotide incorporation opposite the damage by the Klenow fragment of E. coli polymerase I.
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PMID:Synthesis and biochemical properties of cyanuric acid nucleoside-containing DNA oligomers. 1040 3

Emphasis was placed in this work on the assessment of biological features of 2,2,4-triaminooxazolone, a major one-electron and(. )OH-mediated oxidation product of guanine. For this purpose, two oligonucleotides that contain a unique oxazolone residue were synthesized. Herein we report the mutagenic potential of oxazolone during in vitro DNA synthesis and its behavior towards DNA repair enzymes. Nucleotide insertion opposite oxazolone, catalyzed by Klenow fragment exo(-)and Taq polymerase indicates that the oxazolone lesion induces mainly dAMP insertion. This suggests that the formation of oxazolone in DNA may lead to G-->T transversions. On the other hand, oxazolone represents a blocking lesion when DNA synthesis is performed with DNA polymerase beta. Interestingly, DNA repair experiments carried out with formamidopyrimidine DNA N -glycosylase (Fpg) and endonuclease III (endo III) show that oxazolone is a substrate for both enzymes. Values of k (cat)/ K (m)for the Fpg-mediated removal of oxidative guanine lesions revealed that 8-oxo-7,8-dihydroguanine is only a slightly better substrate than oxazolone. In the case of endo III-mediated cleavage of modified bases, the present results suggest that oxazolone is a better substrate than 5-OHC, an oxidized pyrimidine base. Finally, MALDI-TOF-MS analysis of the DNA fragments released upon digestion of an oxazolone-containing oligonucleotide by Fpg gave insights into the enzymatic mechanism of oligonucleotide cleavage.
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PMID:In vitro DNA synthesis opposite oxazolone and repair of this DNA damage using modified oligonucleotides. 1071 Apr 22

1-(2-Deoxy-beta-D-erythro-pentofuranosyl)-5-hydroxy-5-methylhydantoin (5-OH-5-Me-dHyd) (3) has been shown to be a major oxidation product of thymidine formed upon exposure of DNA to (*)OH-radical and excited photosensitizers. To investigate the biological and structural significance of the 5-OH-5-Me-dHyd residue to DNA, the latter modified 2'-deoxyribonucleoside was chemically prepared and then site-specifically incorporated into oligodeoxyribonucleotides. This was efficiently achieved using the phosphoramidite approach that involved mild deprotection conditions. The purity and the integrity of the modified synthetic DNA fragments were checked using different complementary techniques such as HPLC and polyacrylamide gel electrophoresis, together with electrospray ionization and MALDI-TOF mass spectrometry. The piperidine test applied to 5-OH-5-Me-dHyd containing oligonucleotides showed a weak instability of hydantoin nucleoside inserted into the oligonucleotide chain. Several enzymatic experiments aimed at determining the biochemical features of such a DNA lesion were carried out. Thus, processing of 5-OH-5-Me-dHyd by nuclease P(1), snake venom phosphodiesterase, and calf spleen phosphodiesterase was investigated. The specificity and the mechanism of excision of the lesion by several bacterial and yeast DNA N-glycosylases, namely, endonuclease III (endo III), endonuclease VIII (endo VIII), formamidopyrimidine DNA N-glycosylase (Fpg), Ntg1 protein (Ntg1), Ntg2 protein (Ntg2), and Ogg1 protein (yOgg1), were also determined. These repair studies clearly showed that all these enzymes, with the exception of the yOgg1 protein, are able to recognize and remove 5-hydroxy-5-methylhydantoin from the double-stranded DNA fragment. Finally, a 22-mer DNA oligomer bearing a 5-OH-5-Me-dHyd residue was used as a template to study the in vitro nucleotide incorporation opposite the damage by the Klenow fragment of Escherichia coli polymerase I, Taq DNA polymerase, and DNA polymerase beta. Thus, it may be concluded that the oxidized thymine residue is a strongly blocking lesion for the three studied DNA polymerases.
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PMID:Repair and coding properties of 5-hydroxy-5-methylhydantoin nucleosides inserted into DNA oligomers. 1089 89

The whole genome sequences of Helicobacter pylori strain 26695 have been reported. Whole cell proteins of H. pylori strain 26695 cells were obtained and analyzed by two-dimensional electrophoresis, using immobilized pH gradient strips. The most abundant proteins were shown in the region of pI 4.0-9.5 with molecular masses from 10 to 100 kDa. Soluble proteins were precipitated by the use of 0-80% saturated solutions of ammonium sulfate. Soluble proteins precipitated by the 0-40% saturations of ammonium sulfate produced similar spot profiles and their abundant protein spots had acidic pI regions. However, a number of soluble proteins precipitated by more than 60% saturation of ammonium sulfate were placed in the alkaline pI regions, compared to those precipitated by 40% saturation. In addition, we have performed an extensive proteome analysis of the strain utilizing peptide MALDI-TOF-MS. Among the 345 protein spots processed, 175 proteins were identified. The identified spots represented 137 genes. One-hundred and fifteen proteins were newly identified in this study, including DNA polymerase III beta-subunit. These results might provide guidance for the enrichment of H. pylori proteins and contribute to construct a master protein map of H. pylori.
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PMID:Identifying the major proteome components of Helicobacter pylori strain 26695. 1198 66

A new MALDI-TOF based detection assay was developed for analysis of single nucleotide polymorphisms (SNPs). It is a significant modification on the classic three-step minisequencing method, which includes a polymerase chain reaction (PCR), removal of excess nucleotides and primers, followed by primer extension in the presence of dideoxynucleotides using modified thermostable DNA polymerase. The key feature of this novel assay is reliance upon deoxynucleotide mixes, lacking one of the nucleotides at the polymorphic position. During primer extension in the presence of depleted nucleotide mixes, standard thermostable DNA polymerases dissociate from the template at positions requiring a depleted nucleotide; this principal was harnessed to create a genotyping assay. The assay design requires a primer- extension primer having its 3'-end one nucleotide upstream from the interrogated site. The assay further utilizes the same DNA polymerase in both PCR and the primer extension step. This not only simplifies the assay but also greatly reduces the cost per genotype compared to minisequencing methodology. We demonstrate accurate genotyping using this methodology for two SNPs run in both singleplex and duplex reactions. We term this assay nucleotide depletion genotyping (NUDGE). Nucleotide depletion genotyping could be extended to other genotyping assays based on primer extension such as detection by gel or capillary electrophoresis.
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PMID:A novel MALDI-TOF based methodology for genotyping single nucleotide polymorphisms. 1465 8

We report here the design, synthesis and evaluation of a novel photocleavable (PC) biotinylated nucleotide analog, dUTP-PC-Biotin, for DNA polymerase extension reaction to isolate DNA products for mass spectrometry (MS) analysis. This nucleotide analog has a biotin moiety attached to the 5-position of 2'-deoxyribouridine 5'-triphosphate via a photocleavable 2-nitrobenzyl linker. We have demonstrated that dUTP-PC-Biotin can be faithfully incorporated by the DNA polymerase Thermo Sequenase into the growing DNA strand in a DNA polymerase extension reaction and that its incorporation does not hinder the addition of the subsequent nucleotide. Therefore, the DNA extension fragments generated by using the dUTP-PC-Biotin can be efficiently isolated by a streptavidin-coated surface and recovered by near-UV light irradiation at room temperature in mild condition for further analysis without using any chemicals or heat. Single and multiple primer extension reactions were performed using the dUTP-PC-Biotin to generate DNA products for MALDI-TOF MS analysis. Such nucleotide analogs that carry a biotin and a photocleavable linker will allow the isolation and purification of DNA products under mild conditions for MS-based genetic analysis by DNA sequencing or multiplex single nucleotide polymorphism (SNP) detection. Furthermore, these nucleotide analogs should also be useful in isolating DNA-protein complexes under non-denaturing conditions.
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PMID:Design and synthesis of a photocleavable biotinylated nucleotide for DNA analysis by mass spectrometry. 1474 78

Determination of the hepatitis C virus (HCV) genotype has become the standard procedure in laboratory diagnostics of HCV infection. Genotype elucidation has prognostic value assignment helps in assessing disease prognosis and promotes establishing appropriate duration of treatment. Now 11 major genotypes and more than 70 subtypes of HCV have been identified using the sequence variability within 5' non-coding region (5' NCR). In Russia the most common subtypes are 1a, 1b, 2a, 3a and more rare - 4 and 5 types. While the "gold standard" for testing is nucleic acid sequencing, a variety of other assays, including the line probe assay or type-specific amplification, has been developed to provide more rapid and cheaper forms of testing. The aim of this study was to determine the type-specific single nucleotide polymorphism (SNP) in 5' NCR HCV by the classical three-step minisequencing method with followed MALDI-TOF mass spectrometry detection The fragments of 5'NCR of HCV genomes were amplified by the nested RT PCR. The removal of excess nucleotides and primers was performed. Three oligonucleotide primers were design to detect two sets of type-specific SNP in 5' NCR HCV. The primer extension reaction was performed using modified thermostable DNA polymerase and in the presence of ddNTP. The molecular weights of primers extension reaction products were analyzed using MALDI-TOF mass spectrometry. The HCV genotype was determined according the presence in analyses sample the molecules with expected molecular weights. The suggested method was used to type HCV from 69 HCV-positive sera. The 1a genotype was determine in 4.5% samples, 1b - 48%, 2a - 4.5% 3a - 29%, 4 - 1.5%. The mixes of two genotypes were found in 13% samples. All data confirmed by direct nucleic acid sequence. Thus, the new method for HCV typing has been developed using the minisequencing reaction and mass spectrometry for the determination of nucleic acid molecular weight.
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PMID:[Using the mass spectrometry analysis for hepatitis C virus typing]. 1585 Feb 17

Determination of the hepatitis C virus (HCV) genotype has become accepted as the standard procedure in laboratory practice. Genotype assignment helps in disease prognosis and assists in establishing the appropriate duration of treatment. More than 10 types and 70 subtypes of HCV have been described. In Russia the most common subtypes are 1a, 1b, 2a, and 3a, and the types 4 and 5 are relatively rare. The "gold standard" for testing is gene sequencing. However, a variety of other assays had been developed to provide more rapid and cheaper forms of testing. The aim of this study was to determine the HCV genotype by minisequencing followed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Fragments of 5' untranslated region of the HCV genome were amplified. Three oligonucleotide primers were designed to detect two sets of genotype-specific single nucleotide polymorphisms. The primer extension reaction was performed using modified thermostable DNA polymerase and in the presence of dideoxynucleosides. The molecular weights of the reaction products were analyzed with MALDI-TOF mass spectrometer. The HCV genotype was determined by registering the particles of the expected molecular weights. The method was used to genotype HCV from HCV-positive blood sera or plasma. The 1a, 1b, 2a, 3a, and 4 genotype HCVs were determined in the samples examined. The data were confirmed by direct sequencing. Thus, we propose a new accurate and efficient method for HCV genotyping based on minisequencing followed by mass spectrometry.
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PMID:Matrix-assisted laser desorption ionization-time of flight (mass spectrometry) for hepatitis C virus genotyping. 1595 2


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