| 1. |
- Gharizadeh, Baback, et al.
(författare)
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Methodological improvements of pyrosequencing technology
- 2006
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 124:3, s. 504-511
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Tidskriftsartikel (refereegranskat)abstract
- Pyrosequencing technology is a rather novel DNA sequencing method based on the sequencing-by-synthesis principle. This bioluminometric, real-time DNA sequencing technique employs a cascade of four enzymatic reactions producing sequence peak signals. The method has been proven highly suitable for single nucleotide polymorphism analysis and sequencing of short stretches of DNA. Although the pyrosequencing procedure is relatively straightforward, users may face challenges due to varying parameters in PCR and sequencing primer design, sample preparation and nucleotide dispensation; such challenges are labor and cost intensive. In this study, these issues have been addressed to increase signal quality and assure sequence accuracy.
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| 2. |
- Ehn, Maria, et al.
(författare)
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Toward pyrosequencing on surface-attached genetic material by use of DNA-binding luciferase fusion proteins
- 2004
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 329:1, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- Mutation detection and single-nucleotide polymorphisin genotyping require screening of large samples of materials and therefore the importance of high-throughput DNA analysis techniques is significant. Pyrosequencing is a four-enzyme bioluminometric DNA sequencing technology based on the sequencing-by-synthesis principle. Currently, the technique is limited to simultaneous analysis of 96 or 384 samples. Earlier, attempts to increase the sample capacity were made using micromachined filter chamber arrays where parallel analyses of nanoliter samples could be monitored in real time. We have developed a strategy for specific immobilization of the light-producing enzyme luciferase to the DNA template within a reaction chamber. By this approach, luciferase is genetically fused to a DNA-binding protein (Klenow polymerase or Escherichia coli single-stranded DNA-binding (SSB) protein) and to a purification handle (Z(basic)). The proteins are produced in E. coli and purified using cation and anion exchange chromatography with removal of Z(basic). The produced proteins have been analyzed using an assay for complete primer extension of DNA templates immobilized on magnetic beads detected by pyrosequencing chemistry. Results from these experiments show that the proteins bind selectively to the immobilized DNA and that their enzymatic domains were active. Z(basic)-SSB-luciferase produced the highest signal in this assay and was further exploited as enzymatic reagent for DNA sequencing.
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| 3. |
- Eriksson, Jonas, et al.
(författare)
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7-deaza-2 '-deoxyadenosine-5 '-triphosphate as an alternative nucleotide for the pyrosequencing technology
- 2004
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Ingår i: Nucleosides, Nucleotides & Nucleic Acids. - : Marcel Dekker. - 1525-7770 .- 1532-2335. ; 23:10, s. 1583-1594
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Tidskriftsartikel (refereegranskat)abstract
- A new adenosine nucleotide analog suitable for the Pyrosequencing method is presented. The new analog, 7-deaza-2'-deoxyadenosine-5'-triphosphate (c(7)dATP), has virtually the. same low substrate specificity for luciferase as the currently used analog, 2'-deoxyadenosine-5'-O-(1-thiotriphosphate) (dATPalphaS). The inhibitory effect dATPalphaS displays on the nucleotide degrading activity of apyrase was reduced significantly by substituting the c(7)dATP for the dATPalphaS. Both analogs show high stability after long time storage at +8degreesC. Furthermore, with the new nucleotide a read length of up to 100 bases was obtained for several templates from fungi, bacteria and viruses.
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| 4. |
- Nourizad, Nader
(författare)
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Recombinant Enzymes in Pyrosequencing Technology
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pyrosequencing is a DNA sequencing method based on thedetection of released pyrophosphate (PPi) during DNA synthesis.In a cascade of enzymatic reactions, visible light isgenerated, which is proportional to the number of nucleotidesincorporated into the DNA template. When dNTP(s) areincorporated into the DNA template, inorganic PPi is released.The released PPi is converted to ATP by ATP sulfurylase, whichprovides the energy to luciferase to oxidize luciferin andgenerate light. The excess of dNTP(s) and the ATP produced areremoved by the nucleotide degrading enzyme apyrase. The commercially available enzymes, isolated from nativesources, show batch-tobatch variations in activity and quality,which decrease the efficiency of the Pyrosequencing reaction.Therefore, the aim of the research presented in this thesis wasto develop methods to recombinantly produce the enzymes used inthe Pyrosequencing method. Production of the nucleotidedegrading enzyme apyrase by Pichia pastoris expression system,both in small-scale and in an optimized large-scale bioreactor,is described. ATP sulfurylase, the second enzyme in thePyrosequencing reaction, was produced inEscherichia coli. The protein was purified and utilizedin the Pyrosequencing method. Problems associated with enzymecontamination (NDP kinase) and batch-to-batch variations wereeliminated by the use of the recombinant ATP sulfurylase. As a first step towards sequencing on chip-format,SSB-(single-strand DNA binding protein)-luciferase and KlenowDNA polymerase-luciferase fusion proteins were generated inorder to immobilize the luciferase onto the DNA template. The application field for the Pyrosequencing technology wasexpanded by introduction of a new method for clone checking anda new method for template preparation prior the Pyrosequencingreaction. Keywords:apyrase, Pyrosequencing technology, Zbasictag fusion, luciferase, ATP sulfurylase, dsDNAsequencing, clone checking, Klenow-luciferase, SSB-luciferase,Pichia pastoris, Echerichia coli.
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