FastGene Scriptase II

Affordable Reverse Transcriptase in a 4-Step, Ready-Mix Format

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A reverse transcriptase engineered to deliver phenomenal results
How would you construct the ideal reverse transcriptase? It would have to make very long cDNAs at high yields. It would have to be able to work from very small amounts of input RNA. And of course, it would have to work fast. FastGene Scriptase II checks all three boxes, and it does it at a reasonable price. Here’s how. First, mutations are inserted into the RNase H domain of native MMLV‘s reverse transcriptase delivering a higher yield of full-length cDNAs. Next, changes are made to increase the enzymes natural thermal stability providing a more robust enzyme that doesn’t lose processing power, even at elevated temperatures. Finally, the reaction buffer composition is optimized for high speed production of cDNAs from incredibly low levels of input RNA. This unique combination of size, speed, and production makes FastGene Scriptase II  the optimal choice for even the most complex applications requiring cDNAs, such as RT-qPCR and NGS. Here is some !


  • Quantification of Gene Expression
  • RT-qPCR
  • Next Generation Sequencing
  • Low RNA concentration
  • Difficult templates

Longer cDNAs in less time
FastGene Scriptase II has a modified RNase H domain which reduces the active lysis of the template RNA. By slowing this degradation, RT enzyme allows the template to remain intact for just long enough to deliver cDNAs of greater length. It is common to achieve cDNA sizes of up to 12 kBp. The quality of this engineered enzyme is so exceptional that typical incubation times of 50 minutes can be reduced to as little as five.

The ReadyMix format makes it soooo easy!
FastGene Scriptase II comes in three convenient formats. You can purchase the Scriptase II reverse transcriptase with just the bare essentials: 5x RT buffer, dNTPs, DTT, and some RNAse-free water (LS53). You can purchase the complete cDNA synthesis (LS63), which contains everything in the LS53 format plus everything else you’ll need to optimize the perfect cDNA synthesis blend for your particular application: random hexamer primers, oligo dT primers, and RNase inhibitor. The last option is the ReadyMix format (LS64 and LS65), for those labs that need results quickly and without the need to optimize.

Super performance at higher temperatures
A current trend in RT enzyme performance engineering is to withstand very high temperatures  while performing a reverse transcription (50+ °C). FastGene Scriptase II shows a much higher performance even at 42°C. Even at this temperature, FastGene Scriptase II can outperform other high-temp enzymes. Have a look at the comparison data below performed at 55 °C.

Performance comparison of FastGene Scriptase II (green) and a heat-stable reverse transcriptase from Competitor A (orange). FastGene Scriptase II ReadyMix (LS64) and Competitor A´s reverse transcriptase were incubated for 5 to 50 minutes at 42°C or 55 °C, according to the manufacturers recommendations. FastGene Scriptase II ReadyMix outperforms the high-temperature enzyme at every gene and time point.

Expect great results from multi-plex PCR, qPCR, and NGS
The FastGene Scriptase II delivers superior cDNA templates for common downstream applications such as PCR, qPCR, and NGS. The resulting full-length cDNA is of the highest quality and gives a complete picture of the gene and any modification, such as splicing variants. Results using Scriptase II compare very favorably to the most popular brands of reverse transcriptases. For example, complicated multi-plex PCR reactions using cDNA derived from Scriptase II are indistinguishable between brands. In these examples below, GAPDH and YWHAZ were carefully examined via qPCR and both show nearly identical Ct values across a broad range of input RNA concentrations.

Comparison of qPCR results using primers for GAPDH and cDNA produced by using different RNA starting concentration by Competitor I‘s SS-II enzyme   and FastGene Scriptase II at 42 °C.


Comparison of qPCR results using primers for YWHAZ and cDNA produced by using different RNA starting concentration by Competitor I‘s SS-II enzyme and FastGene Scriptase II at 42 °C.

Comparison of different PCR results — multiplex PCR
Comparison of multiplex PCR using cDNA produced by Competitor I‘s SS-II enzyme and FastGene Scriptase II at 42 °C and 50 °C.

Additional Information

FastGene Scriptase II has been used by researchers in Europe and Japan since 2017. Here are few opinions that exemplify how labs are responding to this new reverse transcriptase.

Tübingen University Hospital, Tübingen, Germany on 07/16/2019

We use the Sciptase II Ready Mix and we were more than happy with it! We performed different qPCRs with two different controls (GAPDH and tubulin-b), for both cell lines and patient samples (Biobank frozen biopsy tissue). The results were quite good! The control values were stable compared to our old cDNA protocol, even with less RNA than before. The application and the protocol were very easy!

Kinki University, Osaka, Japan on 07/12/2018

I especially like that the Scriptase II lead to stable results. As a result of performing RT-PCR using tumor derived RNA, we were able to detect the expression of genes whose amplification was unstable with other RT reagents. The Amplification of full-length cDNA has also been confirmed. I would love to also try the 5x Ready Mix.

GIGA Cancer, Liège, Belgium on 09/27/2017

We have tested the RT kit FastGene Scriptase II in comparison with other kits, like Protoscript II (NEB) and Superscipt II (Invitrogen) and we have noted that the results are similar. Additionally, we can make more “runs” for a better price!

LS53 LS63 LS64 LS65
Reactions 100 100 100 100
Contents – FastGene Scriptase II (20,000 U)
– 5x FastGene RT buffer
– DTT (0.1 M)
– dNTP Mixture (2mM each)
– FastGene Scriptase II (200 U/µL)
– 5x FastGene RT buffer
– dNTP Mixture (2mM each)
– Sterile water (RNase free)
– RNase Inhibitor (40 U/µL)
– Oligo dT Primer (80 µM)
– Random hexamer (100 µM)
5x MasterMix containing: FastGene Scriptase II (200 U/µL)
– Reaction buffer
– dNTP Mixture (2mM each)
– RNase Inhibitor (40 U/µL)
– Random hexamer (100 µM)
– Helper Protein
5x MasterMix containing: FastGene Scriptase II (200 U/µL)
– 5x FastGene RT buffer
– dNTP Mixture (2mM each)
– RNase Inhibitor (40 U/µL)
– Random hexamer (100 µM)
– Oligo dT (80 µM)
– Helper Protein
Input RNA
• Total RNA: 1 ng – 1μg
• Messenger RNA (mRNA): 1 ng – 0.25 µg
• Specific RNA: 0.01 pg-0.5 µg
cDNA length up to 12kb
RNase-free Yes
Inhibitor-free Yes
Exonuclease-free Yes
Endonuclease-free Yes
Purity >99% on SDS-PAGE
Storage at -20°C <6 months for ReadyMix (LS64 & LS65), or 1 year  for stand alone enzyme (LS53 & LS63)