ABSTRACT
The T7 RNA polymerase-dependent transcription was studied as a function of nucleotide sequence structures positioned upstream of the T7 promoter. Model double-stranded DNA templates were constructed for this purpose. They contained a target sequence of 485 base pairs (cDNA fragment of Venesuelian encephalomyelitis equine virus genome), T7 promoter consensus and different extra base sequences upstream of the T7 promoter. The level of the target sequence transcription was clearly determined by the extra base sequence. The presence of one extra base pair G.C ensured the most pronounced effect, transcription was increased one order of magnitude in comparison with template which has only a canonical T7 promoter sequence at the 5'-end.
Subject(s)
DNA, Viral/metabolism , DNA-Directed RNA Polymerases/metabolism , Promoter Regions, Genetic , Transcription, Genetic , Base Sequence , Encephalitis Virus, Venezuelan Equine/genetics , Molecular Sequence Data , Polymerase Chain Reaction , RNA, Viral/biosynthesis , Templates, Genetic , Thermus thermophilus , Viral ProteinsABSTRACT
A simple procedure was developed for testing and purification of restriction endonucleases Msp I, Pst I, Bam HI, Pvu I, Pvu II that includes biomass destruction, fractionation of cell-free extracts in the aqueous two-phase (polyethylene glycol-dextran) system and chromatography oh phosphocellulose. Optimal conditions for the fractionation of Msp I, Pst I, Bam HI, Pvu II, EcoR I, EcoR II, BspR I, Alu I were chosen. For separation of Pvu I and Pvu II gel filtration through biogel A-0.5 m was additionally introduced.
Subject(s)
DNA Restriction Enzymes/isolation & purification , Dextrans , Polyethylene Glycols , Chemical FractionationABSTRACT
A purification techniques was developed to obtain a preparation of the bacteriophage T4 RNA-ligase (EC 6.5.1.3) free of contaminating nuclease activities. It includes fractioning on phosphocellulose and DEAE-cellulose, chromatography on DEAE-cellulose, isoelectric sedimentation, gel filtration through Sephadex G-100 and chromatography on hydroxylapatite and aminohexyl-sepharose. The enzyme yield amounts to 30-37%. By means of biochemical tests, the preparation of RNA-ligase was found to be good for molecular biology and gene engineering, in particular for such areas where oligodeoxyribonucleotides and high molecular-weight RNA are used as substrates. The ligating ability of the enzyme was demonstrated by means of the preparative synthesis of nonaribonucleotide ApUpG(pU)6 from trinucleoside diphosphate ApUpG and hexoribouridylic acid, as well as by insertion of [5'-32P]-labelled cytidine-3',5'-diphosphate in the 3'-end of the bacteriophage MS 2 RNA.
Subject(s)
Polynucleotide Ligases/isolation & purification , RNA Ligase (ATP)/isolation & purification , T-Phages/enzymology , Chromatography, DEAE-Cellulose , Chromatography, Gel , Deoxyribonucleases/isolation & purification , Electrophoresis, Polyacrylamide Gel , Isoelectric Focusing , Methods , RNA Ligase (ATP)/analysis , Ribonucleases/isolation & purification , Spectrophotometry, UltravioletABSTRACT
Phenylalanine-specific tRNA from yeast was hydrolysed with cobra venom ribonuclease in the double-stranded regions and the fragments isolated. The 'dissected' molecules with nicks in positions 28 and 41 were reconstructed from supplementary fragments and treated with T-4 RNA ligase. A phosphodiester bond between two fragments was formed when the fragment combination (1-28) + (29-76) was used. A strong discrimination in the ligation yield between different nick positions in the same helix is shown.
