One-step RT-PCR provides a convenient and powerful way for RNA detection and quantification. In the process of one-step RT-PCR, RNA is first transcribed into cDNA by the enzyme with reverse transcription activity, and then it is detected qualitatively by PCR or quantitatively by qPCR under the amplification of the enzyme with DNA polymerase activity. All of these is done in a single tube, which can greatly reduce the potential contaminations. 

The traditional one step RT-PCR carries out the above reactions by two enzymes. The reverse transcription is done by reverse transcriptase like Moloney Murine Leukemia Virus Reverse Transcriptase (M-MLV RT) or Avian Myeloblastosis Virus Reverse Transcriptase (AMV RT). And the DNA polymerization is done by DNA polymerase like Taq DNA polymerase or Pfu DNA polymerase. This two-enzyme system seems to be the most popular one used by researchers worldwide, but it has its own weak point. Because M-MLV RT or AMV RT also have DNA-dependent polymerase activity, in the process of constant temperature reverse transcription, the reverse transcriptase will cause dimer amplification and extension between primers, resulting in the performance degradation of hot start DNA polymerase. This will lead in limited amplification sensitivity and false positive amplification. 

To save the problem caused by the two-enzyme system, scientists have been looking for enzymes which have both reverse transcription activity and DNA polymerase activity. One enzyme isolated from Thermus thermophilus has aroused the interest of all. Tth DNA Polymerase, a thermostable DNA polymerase, has both 5'-3' polymerase activity and 3'-5' exonuclease activity. And in the presence of Mn²⁺, Tth DNA polymerase shows an additional reverse transcriptase activity. This discovery was perceived as a breakthrough in this field. However, the following research showed that the reverse transcription activity of Tth DNA polymerase is not very good, so it cannot be widely used in TaqMan PCR-based gene detection and diagnosis. 

Through hard work of scientists, another enzyme called TTx DNA polymerase is developed. Its reverse transcription activity is much higher than that of Tth DNA polymerase. With high tolerance to PCR inhibitors, TTx DNA polymerase is effective for amplification from crude samples with high efficiency. With mentioned characteristics, TTx DNA polymerase seems very promising. However, like Tth DNA polymerase, the activity of TTx DNA polymerase still depends on Mn²⁺, which has inhibitory activity to PCR. This shortcoming limits the application of this enzyme. 

At SBS Genetech, we are at the forefront of offering comprehensive solutions for PCR-Related products, from basic to advanced. One highlight of our PCR-Related products is our PrimeTaq™ HS DP DNA/RNA Polymerase. Like TTx DNA polymerase, our PrimeTaq™ HS DP DNA/RNA Polymerase has 5'-3' polymerase activity, 3'-5' exonuclease activity and strong reverse transcription activity. However, unlike TTx DNA polymerase, PrimeTaq™ HS DP DNA/RNA Polymerase depends on Mg²⁺ instead of Mn²⁺, so it won’t be limited by its buffer system, and can be used in various applications. Besides, this enzyme has hot start property and high tolerance to many PCR inhibitors. High tolerance delivers convenience for both DNA and RNA amplification by allowing PCR directly from samples without prior purification. With hot start property, the polymerase is 100% inactive below 50°C and can be completely recovered only after heating at 92°C for 5 min. Therefore, the system can effectively inhibit non-specific PCR amplification, greatly improving the specificity and sensitivity. 

One-step RT-PCR have been developing rapidly in recent year, and is now playing a significant role in both scientific research and molecular diagnosis. We are glad to be a part of it. At SBS Genetech, we are committed to providing high quality product for the scientific community, driving the development of science and technology.