Team:ITB Indonesia/Modeling/CYP450AFB1


CYP450 and AFB1 Enzymatic Reaction

When your system is involving enzyme to transform or catalyze some reaction, basically you will need one from two possible kinetic equation : Michaelis-Menten and Hill equation. The basic difference between Michaelis-Menten and Hill equation is the presence of n (hill coefficient) as a result of cooperative binding in Hill equation.

After AFB1 successfully diffused into cell, the next reaction is oxidations catalyzed by cytochrome P450 (CYP450) enzyme. AFB1 is enzymatically activated by CYP450 3A4 to a very reactive form, AFB1 oxide. AFB1 oxide is the genotoxic isomer and reacts efficiently with DNA at the Guanine. In a simple way, this reactive form can damage our cell’s DNA and activated our reporter gene to report the aflatoxin presence.

From the literature, we concluded that enzymatic reaction between AFB1 and CYP450 is more likely to agree with Hill equation. We gathered the value of all parameters we need to simulate this phenomena :






Changing along with CYP450 constitutive synthesis





0,006 M




Depend on AFB1 molecule number in recent time

Source :
[1] Gallagher, E. P., Kunze, K. L., Stapleton, P. L., Eaton, D. L. (1996) The Kinetics of Aflatoxin B1 Oxidation by Human cDNA-Expressed and Human Liver Microsomal Cytochromes P450 1A2 and 3A4. Toxicology and Applied Pharmacology 141, 595–606. Article No. 0326