Hot-start Taq enzyme is widely used. Compared with ordinary Taq enzyme, hot-start Taq enzyme can effectively avoid some non-specific amplification and the formation of primer dimers, and can effectively improve the success rate of target gene amplification. Especially in the field of genetic testing, hot-start Taq enzyme has been identified as a mandatory industry standard, and ordinary Taq enzyme should not be used. As can be seen from the above, hot-start Taq enzymes are widely used. Faced with so many hot-start Taq enzyme products, how should we choose?

Select the hot-start Taq enzyme with high amplification efficiency. PCR amplification efficiency is closely related to the performance of Taq enzyme. After a good Taq enzyme reaction system is optimized, the amplification efficiency is above 95%, and the amplification range of the initial template amount is wide. Satisfactory amplification can be obtained when the target gene content is low, and it is not easy to be poisoned when the template amount is high, and the exponential amplification period is long. For the Taq enzyme with poor performance, even if the reaction system has been optimized for many times, the amplification efficiency is still less than 90%, the "S" shape of the amplification curve is not obvious, the slope is small, and the curve is flat. When the amount of template is low, it cannot be amplified, and when the amount of template is high, the amplification effect is not ideal. Therefore, the selection of Taq enzyme with high amplification efficiency is important for the success of PCR and qPCR. Our laboratory has compared the hot-start Taq enzymes of several companies commonly used in China. The GAPDH plasmid was serially diluted 5 times, and the qPCR results were made into a standard curve. The results showed that the amplification efficiency of ABI and BIOG hot-start Taq enzymes was 95%. % or more, the low amount that can be detected per reaction volume can reach 2pg, while the amplification efficiency of the hot-start Taq enzyme of an internationally renowned brand T is only 90%, and there is no amplification curve when the template amount is 2pg.

Select the hot-start Taq enzyme with strong enzyme kinetics. The enzymatic power of the Taq enzyme is related to the amplification efficiency. Generally, the stronger the enzymatic power of the hot-start Taq enzyme, the longer the exponential growth period of PCR amplification, the more typical 'S-shaped' curve, the higher the fluorescence signal value, and the more suitable for multiplex PCR detection. We have compared the hot-start Taq enzymes of many companies. Among the foreign brands, the hot-start Taq enzyme (Immulase) of the British Bioline company has better enzyme power, can do 4-plex PCR, and the fluorescence signal when the same amount of starting template CT30 is used. high value. Among domestic brands, BIOG hot-start Taq enzyme has a longer exponential period and can do triple PCR, and the 'S' type of the amplification curve is not affected. During the reaction, the amplification curve is low, the fluorescence signal value is low, there is no typical amplification curve, and the result is difficult to judge.

Select a hot-start Taq enzyme with high sensitivity. Generally speaking, the amplification efficiency of Taq enzyme is high, and the sensitivity is high, but there are also inconsistencies. If the target gene abundance of the sample to be amplified is low, it is recommended to test the amplification sensitivity of Taq enzyme. The common detection method is to carry out 10-fold or 5-fold gradient dilution of the target gene plasmid fragment, carry out PCR detection at the lower dilution, and select the hot-start Taq enzyme with higher detection sensitivity.