IGEM:IMPERIAL/2007/new pages/DNA concentrations

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Testing DNA concentration of pTet-LuxR-pLux-GFPmut3b In vitro


To determine if the optimum concentration of pTet-LuxR-pLux-GFPmut3b in vitro.

Materials and Methods

Refer to protocols page.
Tested on (Insert link)


Fig.1.1:DNA Concentration in vitro - The DNA concentration of pTet-LuxR-pLux-GFPmut3b in vitro. The fluorescence was measured adn converted into molecules of GFPmut3b in vitro using our calibration curve.

Fig.1.2:DNA Concentration in vitro after 360 minutes - This graph shows the molecules of GFPmut3b produced after 360 minutes at varying DNA concentrations.


  • Negative Control- Nuclease Free Water was added instead of DNA


  • Temperature - 25°C
  • Total Volume - 60µl

Raw Data


Figure 1.1 and Figure 1.2. shows us that the synthesis of GFPmut3b increases with DNA added up until 4µg of DNA. Above this the number of molecules of GFPmut3b produced decreases.

Another interesting observation is that the 6µg of DNA begins producing GFPmut3b greater than 2µg but then levels of before 2µg. This is thought to be because the data displayed on the figures are averages of 2 samples, one of the samples levels off sooner than the other and so brings the average down. However, the results do tell us that 6µg is lower than the 4µg, therefore the 4µg is the optimum DNA for our in vitro chassis.

This agrees with promegas guide on using the commcerial cell extract in vitro chassis. The guide states that 4µg is the maximum and above this there is problems with premature termination of translational products


To conclude the following approximations can be made:

  • Optimum DNA concentrations - 4µg of DNA