IGEM:Peking/2007/Switch: DNA digestion

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endonuclease enzymatic reaction


There is great influence on enzymatic efficiency by enzymatic buffer. We should choose buffer according to the double digestion form provided by Takara and different activities for different endonuclease in various buffer.

enzymatic temperature

Most endonuclease has the optimal activity temperature of 37℃. There is exceptions such as SmaI's best temperature is 30℃ while SfiI needs 50℃ to work efficiently.

enzymatic system

Includs plasmid/PCR product, enzyme, buffer and water, sometimes with BSA and Trition X-100 in it. The system for enzymatic test should be no more than 20uL. The system for recruiting vectors and fragments should be around 100uL.

enzymatic DNA concentration

The vector concentration should be no more than 1ug, PCR fragment concentration should be no less than 1ug.

Star activity

Some endonuclease will have a less specific substrate selection under certain conditions. It will cut different sequences from original recognitions. This is called star activity.

In order to reduce the star activity, glycero concentration should not be too high and DNA concentration should not be too low. In the storage of enzyme there is glycerol. So the maximal amount of enzyme added in a system should be 10%, especially for enzymes with star activities.

The influence of Methylation

Some endonuclease activity will be affected by methylation of DNA.

There is a methylation form we can refer to.











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