<h2className="center-text">Section 1 ODE Model of Biochemical Reactions</h2>
<h3>1.1 Oxidation of Phenylethylamine</h3>
<p>Firstly, phenylethylamine (PEA) diffuses through the outer membrane of <em>Escherichia coli</em> into the periplasmic space, where it interacts with TynA.</p>
</MathJax.Provider> represents the passive diffusion constant of phenylethylamine. The amount of substance passing through the membrane per unit time is equal to the product of the concentration difference across the membrane and the passive diffusion rate constant.</p>
<p>Subsequently, monoamine oxidase TynA oxidizes phenylethylamine into phenylacetaldehyde (PA) and ammonia.</p>
<p>2. Total Enzyme Concentration: The total concentration of the enzyme is constant and can be expressed as the sum of free enzyme and enzyme bound in the enzyme-substrate complex.</p>
<p>The phenylacetaldehyde and ammonia formed in this reaction cross the inner membrane into the cytoplasm, where they participate in further oxidation and metabolic processes.</p>
<p>The process by which FeaR catalyzes the further oxidation of phenylacetaldehyde into phenylacetic acid (PAA) in the cytoplasm can be broken down into two steps according to the principles of Michaelis-Menten kinetics. The phenylacetic acid produced by the reaction then diffuses out of the cell.</p>
<p>The FeaR-phenylacetaldehyde complex can bind and activate the PTynA promoter. In this case, the concentration of the enzyme-substrate complex <MathJax.Provider>
<p>The activated promoter initiates the transcription of downstream genes, producing the corresponding mRNA, while we also take into account the process of mRNA degradation.</p>
<p>Under the catalysis of GS, glutamate accepts ammonia and is converted into glutamine. Glutamate in the gut diffuses into the cytoplasm, where it is converted into glutamine. The glutamine then diffuses back into the gut, acting as a carrier molecule.</p>
<p>For an enzyme-catalyzed reaction involving two substrates that form a single product, the Michaelis-Menten equation can be extended to account for the involvement of both substrates. The general reaction can be written as</p>
<p>TPH1 converts tryptophan that enters the cytoplasm into 5-hydroxytryptophan, which is then transported from the cytoplasm into the gut. The corresponding reaction equations and ODEs are as follows</p>