Bioengineering/matlab

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Lecture_101018.pptx

Review

1 -1 0 0 0 0 0 0 0 0
0 1 -1 0 0 0 0 0 0 0
0 0 1 -1 -1 0 0 0 0 0
0 0 0 1 -1 0 0 0 0 0
0 0 0 1 0 1 -1 -1 0 0
0 0 0 0 0 0 0 1 -1 0
0 0 0 0 0 0 1 0 1 -1

Draw the pathway

1 -1 0 0 0 0 0 0 0 0
0 1 -1 0 0 0 0 0 0 0
0 0 1 -1 -1 0 0 0 0 0
0 0 0 1 -1 0 0 0 0 0
0 0 0 1 0 1 -1 -1 0 0
0 0 0 0 0 0 0 1 -1 0
0 0 0 0 0 0 1 0 1 -1

1 0 0 0 0 0 0 0 0 -1
0 1 0 0 0 0 0 0 0 -1
0 0 1 0 0 0 0 0 0 -1
0 0 0 1 0 1 0 0 0 -1
0 0 0 0 1 -1 0 0 0 0
0 0 0 0 0 0 1 0 1 -1
0 0 0 0 0 0 0 1 -1 0

rref

Rank:

Nullity:

Dimension:

Free variables:

Find J

E+S

ES

E+P

k1

k-1

k2

k-2

Previously we looked at rapid equilibrium (kp ~ k2) and therefor the [P] depended only on k2[ES] rate.

Michaelis-Menten is useful in calculating enzyme kinetics of a system where a substrate can reversibly bind to an enzyme

Under quasi-steady state assumption, we assume that the change of concentration of the enzyme and enzyme-substrate complex is equal to zero

The maximum velocity is the rate of the reaction at which the enzyme is saturate with substrate

Total enzyme is distributed between E and ES (ET = E + ES)

How to derive Rate Equations

Draw reaction scheme of all steps

Use mass action kinetics to write ODEs for concentration changes such that the right hand side contains all producing and consuming reactions

Determine total enzyme

Use quasi-steady state assumptions and E(total) to derive algebraic equations for concentration of enzyme

The reaction rate v is equal to the rate of product formation

E+S

ES

E+P

k1

k-1

k2

k-2

There enough substrate that ES concentration never really changes (E and ES reach equilibrium)

Enzyme is neither produced nor consumed

5

From Lecture 11: Kinetics of enzymatic reactions

Where is this from?

What assumptions are made if it is quasi-steady state?

Must show how this was attained in project

Example of disease: Tuberculosis

Caused by mycobacterum tuberculosis (MTB)

MTB is an aerobic, nonmotile bacilus

Can remain latent in its host

One of the top ten causes of death around the world

Multiple instances of total drug-resistant TB

Virulence Pathway

Phagocytosis by a macrophage is a multi-step procedure that ensures complete degradation

Once a pathogen is engulfed, it enters a phagosome which then fuses with a lysosome (phagolysosome complex)

The lysosome has all the needed components to digest the pathogen

MTB is able to remain and reproduce in the phagosome and inhibit the formation of the phagolysosome

As a secondary response, the lungs create granulomas to contain the pathogen

Pathway of Interest

The glyoxylate cycle (glyoxylate shunt) is an alternative anabolic pathway to the tricarboxylic acid cycle (TCA).

MTB is able to undergo the glyoxylate bypass in lung granulomas to create complex sugars and survive in the granulomas

For the project, I would compare something like the production of oxaloacetate with and without the glyoxylate shunt and discuss what effect that has on the production of citrate

Operates in low oxygen environments

10

Number Reactions Enzyme vFWD MAX vREV MAX Km1(mM) Km2(mM) Kp1(mM) Kp2(mM)
1 [aca]+[oaa] <--> [coa]+[cit] Citrate Synthase 64.8 0.648 0.05 0.012 0.5 0.12
2 [cit] --> [icit] Aconitase 31.2 0.312 1.8   0.7  
3 [icit] <--> [suc]+[gly] isocitrate lyase 1.172 0.01172 0.145   0.59 0.13
4 [aca]+[gly] <--> [coa] + [mal] malate synthase 20 0.2 0.057 0.03 1 0.1
5 [mal] --> [oaa] malate dehydrogenase 184 1.84 0.833   0.0443  
6 [icit] --> [akg] isocitrate dehydrogenase 10.2 0.102 0.03   0.3  
7 [akg] --> [sca] alpha-ketoglutarate dehydrogenase 9.965 0.09965 0.06   1  
8 [sca] --> [suc] succinyl-Coa synthase 57.344 0.57344 0.1   5  
9 [suc] --> [fa] succinate dehydrogenase 1.02 0.0102 0.15   0.12  
10 [fa] --> [mal] fumarase 87.7 0.877 0.25   2.38  
11 [oaa] -->       0.67      

v in reverse was assumed to be 1/100 of v forward

How do we get vs and vp?

You will have an ODE for each product formed

Group Project

Introduction and Background

Methods for Model Construction

Results

Discussion of Model

Bonus: stoichiometric matrix and J for pathway

Project Suggestions

Glycolysis : Pyruvate Kinase Deficiency

Gluconeogenesis : Fructose-1,6-bisphosphate deficiency

Oxidative Phosphorylation : Cyanide or Malonate Poisoning

Pentose Phosphate Pathway : G6PD Deficiency

Urea Cycle : Ornithine Transcarbamoylase Deficiency

You are free to pick your own pathway and more than one group can have the same pathway.

You are also allowed to do shunts that bacteria can enter into (like glyoxylate shunt or GABA shunt) in stressful environments.

There is a decent amount of freedom to this project, so if you are interested in modeling something not listed, just e-mail me first.