DNA Polymerases

2025/01/13Class Product DNA Polymerase news 10

- Taq DNA Polymerase
  - Origin and Characteristics: It is derived from the thermophilic bacterium Thermus aquaticus. Its optimal reaction temperature is around 72 °C. This high-temperature characteristic makes it highly suitable for use in the polymerase chain reaction (PCR). Because during the PCR process, high-temperature denaturation (usually at 90 – 95 °C) is required repeatedly to unwind the double-stranded DNA, and Taq polymerase can still remain active in the subsequent annealing and extension steps.
  - Application Scenarios: It is the most commonly used DNA polymerase in PCR technology. It is widely used in molecular biology experiments such as gene cloning, gene detection, and mutation analysis. For example, when amplifying specific genes in large quantities for subsequent genetic engineering operations or disease diagnosis, Taq polymerase can efficiently complete the task.
- Pfu DNA Polymerase
  - Origin and Characteristics: It comes from Pyrococcus furiosus and has 3′ – 5′ exonuclease activity, which means it can correct nucleotides that are incorrectly incorporated during DNA synthesis, and its fidelity is higher than that of Taq polymerase.
  - Application Scenarios: It plays an important role in experiments that require high accuracy of DNA sequences, such as high-fidelity gene cloning, amplification of long DNA fragments, and occasions where precise DNA synthesis is needed. For example, when constructing a gene library or cloning genes that are sensitive to mutations, Pfu polymerase is a better choice.
- Klenow Fragment
  - Origin and Characteristics: It is the large fragment produced by proteolytic cleavage of Escherichia coli DNA polymerase I. It retains 5′ – 3′ polymerase activity and 3′ – 5′ exonuclease activity but loses 5′ – 3′ exonuclease activity. These characteristics make it useful in certain specific DNA synthesis and labeling experiments.
  - Application Scenarios: It is often used for filling in the ends of DNA, labeling radioactive isotopes or non-radioactive labels at the 3′ ends of DNA fragments, and so on. For example, when constructing recombinant DNA molecules, if the ends of DNA fragments are not flush, the Klenow fragment can be used to fill them in for subsequent ligation reactions.
RNA Polymerases
- Escherichia coli RNA Polymerase
  - Origin and Characteristics: It exists in Escherichia coli cells and consists of multiple subunits. It can recognize the promoter region on DNA, initiate the transcription process, and synthesize RNA using ribonucleotides (NTPs) as raw materials.
  - Application Scenarios: It is a key tool in the study of gene expression in prokaryotes. It is used to synthesize RNA corresponding to specific genes in vitro transcription systems to study the transcriptional regulation mechanisms of genes. For example, by constructing a DNA template containing the promoter of a specific gene and using Escherichia coli RNA polymerase for in vitro transcription, the transcription products can be analyzed to understand the expression of the gene under different conditions.
- Eukaryotic RNA Polymerase
  - Origin and Characteristics: Eukaryotes have three main types of RNA polymerases (RNA pol I, RNA pol II, and RNA pol III), which are responsible for the transcription of different types of RNA respectively. RNA pol II is responsible for synthesizing mRNA, which plays a key role in gene expression and protein synthesis and is controlled by complex transcription factors and regulatory elements.
  - Application Scenarios: It is widely used in the fields of gene expression regulation in eukaryotic cells, mRNA synthesis and processing, and so on. For example, in the study of the transcription initiation, elongation, and termination processes of eukaryotic genes, as well as in exploring how cells regulate gene expression according to environmental signals, eukaryotic RNA polymerases are indispensable.
- T7 RNA Polymerase
  - Origin and Characteristics: It is derived from the T7 bacteriophage. It has high specificity and high efficiency. It only recognizes and transcribes the promoter sequence of the T7 bacteriophage itself, and its transcription speed is very fast.
  - Application Scenarios: It has important applications in gene expression technologies. For example, it is used for in vitro large-scale synthesis of RNA. By constructing a gene expression vector containing the T7 promoter and adding T7 RNA polymerase and NTPs in vitro, a large number of specific RNA molecules can be rapidly synthesized, which are used in fields such as RNA interference (RNAi) experiments and mRNA vaccine production.