Mutagenesis Chemistry
Mostrando 1-12 de 20 artigos, teses e dissertações.
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1. "Avaliação da atividade clastogênica do resíduo catalítico industrial, por meio do bioensaio de micronúcleos com Tradescantia pallida cv. Purpurea" / Clastogenicity evaluation of industrial catalytic waste using the Tradescantia pallida cv. Purpurea micronucleus biossay (Trad-MCN)
O objetivo deste estudo foi aumentar o banco de dados em relação a resíduos (cake) e efluentes (licor) industriais e o seu nível de clastogenicidade. Este estudo contribuiu para mostrar: a) que o bioensaio com Tradescantia pallida foi sensível para a avaliação da clastogenicidade em mistura complexa de resíduos catalíticos industriais, nunca testado
Publicado em: 2004
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2. Further improvements on the phosphotriester synthesis of deoxyribooligonucleotides and the oligonucleotide directed site-specific mutagenesis of E. coli lipoprotein gene.
Two improvements that greatly enhance the rate of phosphotriester oligonucleotide synthesis are described: 1) use of hindered primary amines, e.g. t-butyl amine for decyanoethylation of oligonucleotide triester intermediates, and 2) a simplified isolation procedure that eliminates the tedious bicarbonate extraction after each condensing reaction. Using the i
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3. Suppression of Chemical Mutagenesis in Bacteriophage T4 by Genetically Modified DNA Polymerases*
Two antimutagenic DNA polymerases of bacteriophage T4 markedly reduce transition mutagenesis by a variety of chemical mutagens. Spontaneous mutation and mutagenesis by 2-aminopurine, 5-bromodeoxyuridine, and thymine deprivation are strongly suppressed. Mutagenesis at G:C sites by ethyl methanesulfonate, and at A:T sites by nitrous acid, is moderately suppres
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4. Controlling the enantioselectivity of enzymes by directed evolution: Practical and theoretical ramifications
A fundamentally new approach to asymmetric catalysis in organic chemistry is described based on the in vitro evolution of enantioselective enzymes. It comprises the appropriate combination of gene mutagenesis and expression coupled with an efficient high-throughput screening system for evaluating enantioselectivity (enantiomeric excess assay). Several such c
National Academy of Sciences.
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5. Targeted gene evolution in Escherichia coli using a highly error-prone DNA polymerase I
We present a system for random mutagenesis in Escherichia coli for the evolution of targeted genes. To increase error rates of DNA polymerase I (Pol I) replication, we introduced point mutations in three structural domains that govern Pol I fidelity. Expression of error-prone Pol I in vivo results in strong mutagenesis of a target sequence encoded in a P
National Academy of Sciences.
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6. Uracil-DNA glycosylase–DNA substrate and product structures: Conformational strain promotes catalytic efficiency by coupled stereoelectronic effects
Enzymatic transformations of macromolecular substrates such as DNA repair enzyme/DNA transformations are commonly interpreted primarily by active-site functional-group chemistry that ignores their extensive interfaces. Yet human uracil–DNA glycosylase (UDG), an archetypical enzyme that initiates DNA base-excision repair, efficiently excises the damaged bas
The National Academy of Sciences.
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7. Efficient Insertion Mutagenesis Strategy for Bacterial Genomes Involving Electroporation of In Vitro-Assembled DNA Transposition Complexes of Bacteriophage Mu
An efficient insertion mutagenesis strategy for bacterial genomes based on the phage Mu DNA transposition reaction was developed. Incubation of MuA transposase protein with artificial mini-Mu transposon DNA in the absence of divalent cations in vitro resulted in stable but inactive Mu DNA transposition complexes, or transpososomes. Following delivery into ba
American Society for Microbiology.
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8. Novel ceftazidime-resistance β-lactamases generated by a codon-based mutagenesis method and selection
Four known and nine new ceftazidime-resistance β-lactamases were generated by a novel, contaminating codon-based mutagenesis approach. In this method, wild-type codons are spiked with a set of mutant codons during oligonucleotide synthesis, generating random combinatorial libraries of primers that contain few codon replacements per variant. Mutant codons ar
Oxford University Press.
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9. Extending the chemistry that supports genetic information transfer in vivo: phosphorothioate DNA, phosphorothioate RNA, 2'-O-methyl RNA, and methylphosphonate DNA.
DNA and RNA are the polynucleotides known to carry genetic information in life. Chemical variants of DNA and RNA backbones have been used in structure-function and biosynthesis studies in vitro, and in antisense pharmacology, where their properties of nuclease resistance and enhanced cellular uptake are important. This study addressed the question of whether
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10. The tyrosyl-DNA phosphodiesterase Tdp1 is a member of the phospholipase D superfamily
The phospholipase D (PLD) superfamily is a diverse group of proteins that includes enzymes involved in phospholipid metabolism, a bacterial toxin, poxvirus envelope proteins, and bacterial nucleases. Based on sequence comparisons, we show here that the tyrosyl-DNA phosphodiesterase (Tdp1) that has been implicated in the repair of topoisomerase I covalent com
The National Academy of Sciences.
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11. Immobilized metal affinity chromatography of DNA.
Many of the most widely employed operations in molecular biology hinge upon the use of single-stranded DNA as a probe or template. Here we report a straightforward method by which to produce long single-stranded DNA molecules using the polymerase chain reaction (PCR) in combination with immobilized metal affinity chromatography (IMAC). We demonstrate that a
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12. A monocysteine approach for probing the structure and interactions of the UmuD protein.
UmuD participates in a variety of protein-protein interactions that appear to be essential for its role in UV mutagenesis. To learn about these interactions, we have initiated an approach based on the construction of a series of monocysteine derivatives of UmuD and have carried out experiments exploring the chemistry of the unique thiol group in each derivat