User:Jonathan Cline/Notebook/Melaminometer/Technical Summary

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Technical Summary of Melamine Detector

Melamine can be metabolized by biochemical/enzymatic process in bacteria and/or other compatible organisms. Using recombinant DNA techniques, plasmids containing genes encoding specific enzymes will be used to modify the target organism (aka: the chassis). There may be one to four enzymes required for metabolism to desired products.

Metabolic Pathway

melamine --(1)--> ammeline --(2)--> ammelide --(3)--> cyanuric acid 

cyanuric acid  --(4)--> biuret --(5)--> allophante --(6)--> 2 NH3 + some CO2

* (1):  melamine deaminase:triA  --^ NH4+ + H2O
* (2):  ammeline aminohydralase:triA  --^ NH4+ + H2O
* (3):  ammelide aminohydralase:trzC  --^ NH4+ + H2O
* (4):  atzD/trzD  --^ NH4+ + H2O
* (5):  atzE  
* (6):  atzF  

Detection Threshold

From the U.S. FDA standards,

  • a level of melamine and its analogues above 2.5 mg/kg is indicative of food adulteration.
  • This 2.5 ppm represents consumption of 0.063 mg/kg bw/d.

The threshold needed for detection is (x mMol) or no greater than 2.5 ppm.

Logical operation

Desired logical operation:

if [ melamine plus cyanuric acid > threshold ] 
  express RFP  ; or other reporter
  repress RFP  ; or other reporter