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)

MutS, a DNA mismatch-binding protein, seems to be a promising tool for mutation detection. We present three MutS based approaches to the detection of point mutations: DNA retardation, protection of mismatched DNA against exonuclease digestion, and chimeric MutS proteins. DNA retardation in polyacrylamide gels stained with SYBR-Gold allows mutation detection using 1-3 microg of Thermus thermophilus his6-MutS protein and 50-200 ng of a PCR product. The method enables the search for a broad range of mutations: from single up to several nucleotide, as mutations over three nucleotides could be detected in electrophoresis without MutS, due to the mobility shift caused by large insertion/deletion loops in heteroduplex DNA. The binding of DNA mismatches by MutS protects the complexed DNA against exonuclease digestion. The direct addition of the fluorescent dye, SYBR-Gold, allows mutation detection in a single-tube assay. The limited efficiency of T4 DNA polymerase as an exonuclease hampers the application of the method in practice. The assay required 300-400 ng of PCR products in the range of 200-700 bp and 1-3 microg of MutS. MutS binding to mismatched DNA immobilised on a solid phase can be observed thanks to the activity of a reporter domain linked to MutS. We obtained chimeric bifunctional proteins consisting of T. thermophilus MutS and reporter domains, like beta-galactosidase or GFP. Very low detection limits for beta-galactosidase could theoretically enable mutation detection not only by the examination of PCR products, but even of genomic DNA.
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PMID:MutS as a tool for mutation detection. 1608 11

SELEX stands for systematic evolution of ligands by exponential enrichment. This method, described primarily in 1990 [Ellington, A.D., Szostak, J.W., 1990. In vitro selection of RNA molecules that bind specific ligands. Nature 346, 818-822; Tuerk, C., Gold, L., 1990. Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase. Science 249, 505-510] aims at the development of aptamers, which are oligonucleotides (RNA or ssDNA) binding to their target with high selectivity and sensitivity because of their three-dimensional shape. Aptamers are all new ligands with a high affinity for considerably differing molecules ranging from large targets as proteins over peptides, complex molecules to drugs and organic small molecules or even metal ions. Aptamers are widely used, including medical and pharmaceutical basic research, drug development, diagnosis, and therapy. Analytical and separation tools bearing aptamers as molecular recognition and binding elements are another big field of application. Moreover, aptamers are used for the investigation of binding phenomena in proteomics. The SELEX method was modified over the years in different ways to become more efficient and less time consuming, to reach higher affinities of the aptamers selected and for automation of the process. This review is focused on the development of aptamers by use of SELEX and gives an overview about technologies, advantages, limitations, and applications of aptamers.
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PMID:SELEX--a (r)evolutionary method to generate high-affinity nucleic acid ligands. 1762 83

Highly degraded human DNA is commonly encountered in the forensic studies. Despite many efforts, the poor quality and quantity of the DNA often result in unsuccessful DNA analysis. There has been no extensive evaluation of DNA polymerase performance for the successful PCR of highly degraded DNA samples. We evaluated the most efficient DNA polymerases, based on real-time PCR and agarose gel electrophoresis analyses for a single copy gene amplification, with 200 ancient DNA (aDNA) samples of various origins. Nine commercially available DNA polymerases were tested, which included enzymes that are reportedly effective for PCR-inhibitory samples. The first screening test for the polymerases with 20 aDNA samples showed that Pico Maxx HF, FastStart Taq, and Ex Taq HS DNA polymerases were the most effective. Further tests with 180 aDNA samples showed that AmpliTaq Gold (control) amplified PCR products from 52 aDNA samples, PicoMaxx HF from 62, FastStart Taq from 64, and Ex Taq HS from 65. The use of two or more of Ex Taq HS, FastStart Taq, and PicoMaxx HF resulted in a significantly higher success rate than that of AmpliTaq Gold alone. With 37 positive samples tested in duplicate, Ex Taq HS showed the highest reproducibility (13 samples) and AmpliTaq Gold, the lowest (four samples); this difference was significant. The data also showed preferential amplification by the enzymes; Ex Taq HS exclusively produced amplification from two samples, FastStart Taq from one, and PicoMaxx HF from one. We suggest that the initial use of these three DNA polymerases will increase the probability of successfully amplifying DNA from highly degraded human DNA samples.
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PMID:Extensive evaluation of DNA polymerase performance for highly degraded human DNA samples. 2591 82

Inhibitors of polymerase chain reaction (PCR) amplification often present a challenge in forensic investigations of e.g., terrorism, missing persons, sexual assaults and other criminal cases. Such inhibitors may be counteracted by dilution of the DNA extract, using different additives, and selecting an inhibitory resistant DNA polymerase. Additionally, DNA in forensic samples is often present in limited amounts and degraded, requiring special analyses of short nuclear targets or mitochondrial DNA. The present study evaluated the enzymes AmpliTaq Gold, HotStarTaq Plus, KAPA3G Plant, and KAPA2G Robust, with regard to their ability to overcome inhibitory effects. Our data showed that diluting the extracts and adding bovine serum albumin may increase the yield of the PCR product. However, the largest impact was observed when alternative enzymes were utilized, instead of the commonly used AmpliTaq Gold. KAPA2G Robust presented the highest amplification efficiency in the presence of the inhibitor ammonium nitrate. Moreover, the KAPA3G Plant enzyme had the highest efficiency in amplifying degraded DNA from old buried bone material. KAPA3G Plant and KAPA2G Robust may thus be useful for counteracting inhibitors and improving the analysis of challenging samples.
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PMID:Comparison of DNA polymerases for improved forensic analysis of challenging samples. 2729 90