Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A convenient and rapid technique for preparing radiolabeled single-stranded DNA hybridization probes has been developed. Single-stranded recombinant M13 phage DNA containing the mRNA strand of a cloned cDNA is bound to diazobenzyloxymethyl-cellulose in a manner that permits the synthesis of a complementary DNA using reverse transcriptase and primed with either oligo(dT) or the M13 single-stranded primer. A procedural advantage is that after synthesis the unincorporated radiolabeled nucleotides are washed away easily, and the radiolabeled single-stranded DNA probe is eluted with formamide, ready for use. To limit the DNA copy to the insert, a preliminary synthesis reaction is performed with unlabeled nucleotides, primer, and enzyme, followed by digestion of the reaction mix with a restriction endonuclease that recognizes a unique site in the recombinant immediately upstream of the cDNA insert. After elution of the unlabeled synthesized complementary DNA, a second synthesis reaction yields highly radiolabeled single-stranded DNA that extends only the length of the mRNA insert. A major advantage is that the restriction enzyme-cleaved, cellulose-bound template can be stored and reused repeatedly.
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PMID:Synthesis of single-stranded hybridization probes from reusable DNA templates bound to solid support. 620 47

The fungus Fusarium solani detoxifies cyanide through induction of the cyanide hydratase gene activity (chy) in the presence of either KCN or the metal-complexed cyanides, K2Ni(CN)4 or K4Fe(CN)6, at pH 7.0 and 4.0 respectively. Sequence analysis of the chy gene identified primers for reverse transcriptase-polymerase chain reaction (RT-PCR)-directed analysis of mRNA transcripts, which demonstrated that activity correlated to the substrate-specific induction of gene expression. chy transcription was initiated 30-60 min after exposure of F. solani cultures to cyanide complexes. Maximum expression was detected within 4.5 h, after which chy mRNA synthesis declined below the limits of detection within 26 h. A lag period of approximately 2 h, following initial transcription, was recorded before cyanide complexes were converted to formamide. mRNA transcripts of chy were not detected in the absence of cyanide or cyanide complexes. The presence of introns within the gene resulted in a difference in size of 100 bp for DNA compared with mRNA of the corresponding 5' region. This size difference facilitated PCR detection of gene and transcript respectively. Comparisons of the predicted amino acid sequence of the F. solani chy gene and those of Gloeocerospora sorghi, Fusarium lateritium and Leptosphaeria maculans demonstrate that cyanide hydratase genes are highly conserved and of a similar evolutionary origin. These data predict that the functional assay described here to monitor the induction of chy gene expression and, potentially, cyanide degradation would be applicable to a variety of polluted environments.
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PMID:Substrate-regulated cyanide hydratase (chy) gene expression in Fusarium solani: the potential of a transcription-based assay for monitoring the biotransformation of cyanide complexes. 1200 Mar 18

Expression analysis using microarray technology implies a complex experimental procedure with a large number of parameters affecting the final result. We have demonstrated that optimization of such a complex protocol can be far better handled using design of experiments (DOE) than by working on a single parameter at a time. Based on the results of a screening design, we developed a spotting buffer composed of formamide, betaine and nitrocellulose. This buffer provides a 2-fold increase in signal-to-background ratio compared to 3x SSC. Comparison to seven other buffers tested on 10 different substrates revealed it had the highest sensitivity. DNA dissolved in this buffer can be spotted on epoxysilane-coated microscope slides at a density of up to 70 000 spots per slide. A second DOE approach characterized the RNA labeling process with regard to the concentration of fluorescent dyes, dNTPs and reverse transcriptase. Adjust ments of the concentrations of dNTPs, as well as reverse transcriptase, towards the optimum, produced an improvement in the performance of the labeling procedure by a factor of 3 (Cy3) and 10 (Cy5). These results demonstrate that the process of establishing a stable expression profiling protocol and its further optimization can be significantly shortened and improved by DOE.
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PMID:Optimization of high-density cDNA-microarray protocols by 'design of experiments'. 1279 56

Expression of telomerase, the specialized reverse transcriptase that adds 5'-TTAGGG-3' repeats to the ends of human chromosomes, is upregulated in > or =85% of human cancers and tumor cell lines. We describe a direct primer-extension activity assay for human telomerase that displays sensitivity to approximately 10(6) telomerase-positive cells, making the method suitable for use with standard cell culture-based research (Fig. 1). Telomerase is first immunoaffinity purified from cell lysate using an antibody to telomerase and captured using protein G-agarose beads (Steps 14-17). Then telomerase is dissociated from the beads using excess peptide antigen (Step 19). A second affinity purification exploits the stable binding interaction between human telomerase and the telomeric DNA substrate 5'-(TTAGGG)3-3' (dissociation half-life > or = 10 h at 23 degrees C). Modifying neutravidin beads with 5'-biotin-CTAGACCTGTCATCA(TTAGGG)3-3' (Step 5) generates an affinity reagent that captures >90% of immunopurified telomerase (Step 22), providing highly enriched telomerase bound to its DNA substrate in a volume of 20 mul of beads. Addition of assay buffer results in extension of the bead-immobilized DNA substrate (Step 24). Telomerase extension products are released by heating in denaturing formamide buffer to disrupt the avidin-biotin interaction, and then separated and visualized by standard techniques.
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PMID:A sensitive direct human telomerase activity assay. 1837 94

Inhibitor resistance of several commercial Moloney murine leukemia virus reverse transcriptase (MMLV RT) enzymes was investigated. IC(50) values were determined for potential RNA contaminants, including guanidine thiocyanate, ethanol, formamide, ethylenediaminetetraacetic acid (EDTA), and plant-related acidic polysaccharides. Sensitivity (as judged by MMLV RT IC(50) values) was directly correlated to the outcome of "mock" reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays carried out with exogenous inhibitors. MMLV RT enzymes lacking RNase H activity were shown to be more sensitive to RT-qPCR inhibitors. In contrast, a thermal-resistant MMLV RT pentuple mutant (E69K/E302R/W313F/L435G/N454K) showed higher tolerance to these substances than the wild type. Increased resistance was also noted in RT-qPCR comparisons employing crude cell lysates.
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PMID:Mutant of Moloney murine leukemia virus reverse transcriptase exhibits higher resistance to common RT-qPCR inhibitors. 2010 Apr 52

The aim of this study is to explore the advantages of using human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) in cDNA synthesis. Recombinant HIV-1 group M (HIV-1 M) RT and HIV-1 group O (HIV-1 O) RT were produced in an Escherichia coli expression system. In the incorporation of dTTP into poly(rA)-p(dT)(15) (T/P), the K (m) values for dTTP of HIV-1 M RT and HIV-1 O RT were 8 and 12 % of that of Moloney murine leukemia virus (MMLV) RT, respectively, and the K (m) values for T/P were 25 and 23 % of that of MMLV RT, respectively. Compared with MMLV RT, HIV-1 M RT and HIV-1 O RT were less susceptible to formamide, which is frequently used for cDNA synthesis with a G + C-rich RNA to improve specificity. The high substrate affinity and low susceptibility to formamide of HIV-1 RT might be advantageous for its use in cDNA synthesis.
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PMID:Enzymatic characterization of human immunodeficiency virus type 1 reverse transcriptase for use in cDNA synthesis. 2314 16


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