## 3 Results and Discussion
### Quantum Chemical Calculations
As can be observed in Table 5, the reactivity parameters obtained for AFB1 after the docking calculations using several PDB IDs for CYP3A4 show a slight difference in their HOMO and LUMO energy values. This can be attributed to the electronic density rearrangements during the interaction with different amino acids in the active site. These values of the HOMO and LUMO energies lead to different values of the reactivity parameters. Table 6 shows the \(\Delta\)N calculated for each residue. They match with the results obtained using the 1 TQN file. It is important to note that each PDB file presented different conformations inside the active site. As mentioned in the Section 2.4, positive values of \(\Delta\)N indicate that the compound is an electron donor, while negative values indicate that the compound is an electron acceptor. As noted in Table 6, all the calculated values of \(\Delta\)N using different PDB IDs are positive, which means that once the ligand is inside the active site, it acts as an electron acceptor, while the protein residues behave as electron donors. These \(\Delta\)N values could highlight the oxidative process involved in the chemical reaction occurring inside the active site. Figure 6 shows the calculated \(\Delta\)N of each residue of CYP3A4 when they are in contact with the ligand AFB1. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Residue/PDB** & **1 TQN** & **1W0E** & **20 VM** & **4 NY4** \\ \hline ARG105 & 0.048 & – & 0.027 & – \\ SER119 & 0.014 & 0.031 & 0.025 & – \\ ARG212 & 0.027 & – & – & 0.012 \\ ARG212-PHE213 & – & 0.22 & – & – \\ THR309 & 0.032 & – & 0.032 & 0.016 \\ ALA305 & 0.041 & 0.126 & – & – \\ ALA370 & 0.042 & – & 0.042 & 0.026 \\ ARG372-LEU373-GLU374 & 0.142 & – & 0.118 & – \\ ARG372 & – & – & – & 0.017 \\ HER & 0.816 & 0.892 & 0.852 & 0.687 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Fractional number of transferred electrons (\(\Delta\)N) calculated for the interactions between AFB1 and the CYP3A4 protein (using different PDB IDs). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Residue** & **PDB** & **\begin{tabular}{c} **EHOMO** \\ **(eV)** \\ \end{tabular} & **\begin{tabular}{c} **ELUMO** \\ **(eV)** \\ \end{tabular} & **\begin{tabular}{c} **Electron** \\ **Affinity** \\ **(eV)** \\ \end{tabular} & **\begin{tabular}{c} **Ionization** \\ **Potential** \\ **(eV)** \\ \end{tabular} & **\
\begin{tabular}{c} **Hardness** \\ **(eV)** \\ \end{tabular} & **
\begin{tabular}{c} **Chemical** \\ **Potential** \\ **(eV)** \\ \end{tabular} \\ \hline \multirow{4}{*}{ALA370} & 1 TQN & –7.1631 & –0.8740 & 0.8740 & 7.1631 & 3.1445 & –4.0186 \\  & 1W0E & \multicolumn{4}{c}{Not present} & \\  & 20 VM & –7.2899 & –0.7562 & 0.7562 & 7.2899 & 3.2668 & –4.0231 \\  & 4 NY4 & –7.1765 & –0.9069 & 0.9069 & 7.1765 & 3.1347 & –4.0417 \\ \hline \multirow{4}{*}{ARG372} & 1 TQN & \multicolumn{4}{c}{Not present} & \\  & 1W0E & \multicolumn{4}{c}{Not present} & \\  & 20 VM & \multicolumn{4}{c}{Not present} & \\  & 4 NY4 & –7.4102 & –0.8628 & 0.8628 & 7.4102 & 3.2736 & –4.1365 \\ \hline \multirow{4}{*}{ARG372-LEU373} & 1 TQN & –5.8205 & –0.3096 & 0.3096 & 5.8205 & 2.7554 & –3.0651 \\  & 1W0E & \multicolumn{4}{c}{Not present} & \\  & 20 VM & –5.8007 & –0.9638 & 0.9638 & 5.8007 & 2.4184 & –3.3822 \\ \cline{1-1}  & 4 NY4 & \multicolumn{4}{c}{Not present} & \\ \hline \multirow{4}{*}{HEM} & 1 TQN & –0.6215 & 0.4008 & –0.4008 & 0.6215 & 0.5111 & –0.1103 \\  & 1W0E & –0.0157 & 0.6718 & –0.6718 & 0.0157 & 0.3438 & 0.3280 \\ \cline{1-1}  & 20 VM & –0.2140 & 0.8375 & –0.8375 & 0.2144 & 0.5260 & 0.3115 \\ \cline{1-1}  & 4 NY4 & –0.9382 & 0.4794 & –0.4794 & 0.9382 & 0.7088 & –0.2293 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._3.2 Chemical Reactivity and Charge Transfer Calculations (\(\Delta\)N) for Protein CYP1A2 (2 HI4 PDB) with AFB1  
In order to obtain the chemical reactivity parameters described in Table 7, all the amino acids involved in the interaction between AFB1 and CYP1A2 were isolated.