Thermus thermophilus (Tth) DNA Polymerase might be used:
to amplify DNA fragments by polymerase chain reaction (PCR) due to its resistance towards prolonged incubations at high temperatures (95 °C)
to label DNA fragments with either radiolabeled nucleotides, digoxigenin, or biotin, since this enzyme accepts modified deoxyribonucleotides as substrates
to efficiently transcribe RNA targets into cDNA due to its intrinsic Mn-dependent reverse transcriptase (RT) activity
for real time PCR
一般的な説明
Tth DNA Polymerase is isolated from the thermophilic eubacterium Thermus thermophilus HB8, and is purified to be free of nonspecific DNases and RNases. The enzyme is a highly processive 5′-3′ DNA polymerase, and lacks 3′-5′ exonuclease activity. The enzyme exhibits its highest activity at a pH of approximately 9 (adjusted at +25°C), and temperatures around +75°C. It is resistant to prolonged incubations at high temperatures (+95°C).
Biochem/physiol Actions
Thermus thermophilus (Tth) DNA Polymerase is a thermostable DNA polymerase with intrinsic reverse transcriptase (RT) activity. The enzyme is a highly processive 5′-3′ DNA polymerase and lacks 3′-5′ exonuclease activity (proof reading). It was found to possess a very efficient intrinsic reverse transcriptase (RT) activity in the presence of manganese ions – much higher than that demonstrated for Escherichia coli DNA polymerase I and Taq DNA Polymerase. The RT activity is not associated with RNase H activity. The elevated temperatures of Tth DNA Polymerase (optimum +55°C to +70°C, maximum +95°C) activity overcomes the problems posed by RNA secondary structure. Resulting cDNA can be amplified by PCR using the same enzyme in the presence of Mg2+-ions. The ability of Tth DNA Polymerase to perform both reverse transcription and DNA amplification at elevated temperatures allows this enzyme to be used for quantitative RT-PCR, cloning, and gene expression analysis of cellular and viral RNA. Tth DNA Polymerase is used for RT-PCR amplification of RNA up to 1kb.
