Since we will use the fluorescence protein to track the gene expression, we would like to check the effect of uric acid on the signal of fluorescence protein . Since uric acid can alter the pH value, it may interfere the folding of chromoprotein and lower its signal. The two reporter gene that we chose to characterize are mRFP(BBa_E1010) and GFP(BBa_E0040) . Briefly, J61002 and I20260 DH5a colonies expressing mRFP and GFP were picked to grow in 5ml LB solution overnight. The starter cultures were inoculated into 200ml LB and allowed to grow for 6 hours. The total protein was extracted by freeze-thaw method and finally diluted into 1XPBS with different uric acid concentration to acquire an absorbance lower than 1. The absorbance of mRFP and GFP was measured at 607 nm and 515nm respectively. According to the result, uric acid has a very little effect on the fluorescence signal. Color of the chromoprotein could still be retained even if the uric acid is saturated. This indicate that our system is possible to track the gene expression.