Chemotaxis: Another go Chrisantha Fernando Systems Biology Centre Birmingham University Chrisantha Fernando Systems Biology Centre Birmingham University
= Active Tar = Methyl group = Inactive Tar TUMBLE Now add Chemoattractant RUN CheY-P CheY CheB-P CheB Motor CheA
Tumbling via CheY CheA-P RmRm R
RmRm R CheBPCheB S CheAP CheA
RmRm R CheBPCheB S CheAP CheA Use MM kinetics to describe each of the enzyme reactions i.e.
RmRm R CheBPCheB S CheAP CheA
Initial values Parameters Methylation and De-methylation is ‘Saturated’ [R] Rate of reaction per unit CheBP concentration
[S] [R m ] = Methylated Receptor [CheA-P] ≈ tumbling frequency [CheB-P]
[R m ] = Methylated Receptor The limit of perfect adaptation occurs when new R m can no longer be produced
[S] Non-saturated methylation and demethylation No-perfect adaptation.
The First (wrong) Model Available at…
Moving on… We can go through points that were confusing again… It is important you understand the principles of how to model these systems.. Mass action kinetics MM kinetics Inhibition (competitive and non-competitive) Saturation of enzymes We can go through points that were confusing again… It is important you understand the principles of how to model these systems.. Mass action kinetics MM kinetics Inhibition (competitive and non-competitive) Saturation of enzymes
Stochastic Modeling So far we have been doing deterministic modeling. Stochastic models consider individual molecules, undergoing discrete reaction events. These models diverge when particle numbers are low. By the end of this course you will be able to model both using ODEs and stochastic modeling, all the circuits I’ve talked about previously, and more. For now, familiarize yourself with bionetS. So far we have been doing deterministic modeling. Stochastic models consider individual molecules, undergoing discrete reaction events. These models diverge when particle numbers are low. By the end of this course you will be able to model both using ODEs and stochastic modeling, all the circuits I’ve talked about previously, and more. For now, familiarize yourself with bionetS.
BioNetS Easy to use
Here is a paper written using the tool…
Lets start with some simple chemical networks…
CheZ RCheZ R Rm Example of a Saturated Enzyme (CheZ) acting to methylate R