Team:Monash Australia/Modelling

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<H3> Graphs and results </H3>
<H3> Graphs and results </H3>
[[Image:Mrnagraph.png|300px|thumb|left|Figure 5: Production of mRNA in the cell]] The rate at which mRNA is produced can be seen to start off at a rapid rate. However as time goes on the mRNA can be seen to reach a steady state.<p></p>

Revision as of 11:20, 27 October 2010





Kinetic modelling of the ethylene generator


Aims of the Kinetic Modelling

-To determine the maximum output of ethylene

-To estimate HCN levels and assess potential damage to cell


Model 1

Introduction to Model 1

Figure 2: A visual construction of Model 1 using Tinkercell

This model was designed to be the starting point of the our kinetic modelling. Therefore it was decided to begin with a realitivly simple construct.This uncomplicated system could then be used to obtain an ethylene output. This design comprised only of three enzymes and lacked the transcription and translation stages. The enzymes invloved were SAM synthetase, ACC synthase and ACC oxidase or EFE (ethylene forming enzyme). These enzymes were present at fixed concentrations (10, 100, 1000 and 3000 uM) and in a 1:1:1 ratio. This ensured that the model was plain yet ultimately obtained a resonable yet simple ethylene output. Therefore with fixed enzyme concentrations the rate at which ethylene is produced depends on the Vmax of the specific enzymes.

This specific rate is defined by the Michaelis-Menton Equation

             km + [substrate]

Assumptions for Model 1

- A 1:1:1 steady state of enzymes

- No production inhibition

-Substrates (ATP, L-Methionine etc) kept at a constant value due to homeostatic mecahnisms in E.coli

- The best value (km, kcat etc) was always chosen to ensure maxiumum yield of ethylene

Parameters and Values used

Met concentration - 150 uM

ATP concentration - 9600 uM

O2 concentration - 442 uM

SAMsynth Km(Met)- 92 uM

ACCsynth Km(AdoMet)- 37 uM

EFE Km(ACC)- 12 uM

SAMsynth turnover rate (kcat)- 1.5 per second

ACCsynth turnover rate (kcat)- 18 per second

EFE turnover rate (kcat) - 5.9 per second

Graphs and results

Figure 3: Ethylene Production at different steady state concentration

Using Tinkercell a graphical representation of 'Model 1' was generated (Figure 3) using deterministic stimulation. in this figure a graphical representation of the rates, generated internally by the program, of ethylene production are shown for each fixed enzyme concentration assumed. as a result not only is production of ethylene shown to be increasing linearly with time, but at a greater rate with increasing concentration of enzyme (SAM synthetase, ACC synthase, EFE) used,.


Model 2


Model 2 explores the more complicated version of our kinetic modelling. It aims to incorporate the transcription and translation rates of the cell into the final design. This calculation begins to become more difficult due to problomatic degredation,transcription and translation rates. However these values where obtained from the Elowitz repressilator model. Of the many sources browsed it was determined that this source seemed to be the most accurate and hence its values were used. Therefore the transcription and translation rates of mRNA and proteins constantly changes the final concentration of the three enzymes. This changing concentration of enzymes then produces ethylene at a more reliable rate. Therefore this model is designed to produce a more accurate representation of the ethylene producing biological pathway

Elowitz Degradation Values

mRNA degradation rate - 0.00577 mRNA per second

Enzyme degradation rate - 0.001155 enzymes per second

R0011 PoPs or transcription rate - 0.5 mRNA per second

Translation rate -0.117 enzymes per second

Graphs and results

Figure 5: Production of mRNA in the cell

Figure 6: Production rate of the three different enzymes

Figure 7: Ethylene production at floating enzyme concentration

The production of ethylene in this graph looks realitively accurate however due to the confunding aspects of excess enzyme production then it is unclear if this graph truely represents the total ethylene output. However it can be assumed that the first few seconds accurately portray the ethylene output.



Met --> SAM (AdoMet)

Met sam.jpg


Sam acc.jpg

ACC --> Ethylene

Acc eth.jpg

More to come soon!