# In-Silico Characterization of von Willebrand Factor Bound to FVIII
## 3 Results
### Interface Analysis
); indeed, PCN parameters have been in accordance with experimental data and PISA calculations. These differences were mirrored by other topological PCN parameters, i.e., \(\sum\mathbf{k}_{A_{i}A_{j}}^{\mathbf{EM}}\) the average value of the interaction energy. Particularly in the comparison between \(\acute{\text{e}}\)fanesoctocog alfa and BDD-FVIII, we found subtle differences in graph energy parameters regarding topology of protein-protein interfaces. Therefore, we carried out PCN clustering and participation coefficient (\(P\)) calculation, in order to identify through a quantitative approach (see method section, i.e., 2.3 Network clustering and participation coefficient calculations) residues involved in allosteric modulation of protein structure, i.e., allosteric residues (Figures 5-7). The VWF/FL-FVIII (around 1%, Figure 5) complexes showed the lowest number of allosteric residues, compared to the VWF/BDD-FVIII (about 4%, Figure 6) and the \(\acute{\text{e}}\)fanesoctocog alfa (more than 5%, Figure 7). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & Q\({}_{A_{i}}\) & (\(\frac{Q}{R}\))\({}_{A_{i}}\) & \(\mathbf{IAR}_{A_{i}}\) & \(\mathbf{E}_{A_{i}A_{j}}\) & \(\sum\mathbf{k}_{A_{i}A_{j}}\) & \(\mathbf{<}\mathbf{k}_{A_{i}A_{j}}\)\(\mathbf{>}\) & \(\sum\mathbf{k}_{A_{i}A_{j}}^{\mathbf{EM}}\) & (\(\mathbf{k}_{A_{i}A_{j}}^{\mathbf{EM}}\)) \\ \hline \multicolumn{8}{c}{**\(\acute{\text{e}}\)fanesoctocog alfa (PDB: 7 WKO)**} \\ \hline
**H** & 63 & 0.13 & 0.85 & 42.86 & 144 & 1.17 & 21.10 & 0.17 \\
**L** & 60 & 0.11 & 0.88 & 42.86 & 144 & 1.17 & 21.10 & 0.17 \\ \hline
**L** & 44 & 0.08 & 0.87 & 31.20 & 95 & 1.07 & 14.29 & 0.16 \\
**V** & 45 & 0.14 & 0.67 & **VWF/FL-FVIII** & & & & \\ \hline
**L** & 662 & 0.37 & 0.94 & 81.07 & 4442 & 3.41 & 21.1 & 0.18 \\
**H** & 641 & 1.00 & 1.00 & 81.07 & 4442 & 3.41 & 21.1 & 0.18 \\ \hline
**H** & 31 & 0.13 & 0.38 & 22.66 & 75 & 1.15 & 8.97 & 0.20 \\
**V** & 34 & 0.11 & 0.72 & **VWF/BDD-FVIII** & & & & \\ \hline
**H** & 54 & 0.10 & 0.82 & 40.49 & 146 & 1.27 & 21.42 & 0.19 \\
**L** & 61 & 0.11 & 0.84 & 40.49 & 146 & 1.27 & 21.42 & 0.19 \\ \hline
**L** & 33 & 0.14 & 0.36 & 28.92 & 94 & 1.32 & 14.31 & 0.20 \\
**V** & 38 & 0.12 & 0.75 & 28.92 & 94 & 1.32 & 14.31 & 0.20 \\ \hline \end{tabular}
\end{table} 
Table 6: **Topological descriptors for the complex interfaces. **\(\mathbf{Q}\) is the total number of residues for each chain in the interface. \(R\) is the length of the chain involved in the interface. \(Q\)/\(R\) is the interface “roughness.” \(\mathbf{IAR}\) = \(\mathbf{R}\)/\(N\) is the interface amino acid range, where \(N\) is the total number of residues in the chain. \(\mathbf{E}_{A_{i}A_{j}}\) is the graph energy of the interface. \(\sum\mathbf{k}_{A_{i}A_{j}}\) is the inter-chain degree. \(<\mathbf{k}_{A_{i}A_{j}}\)\(>\) is the average value of the inter-chain degree. \(\sum\mathbf{k}_{A_{i}A_{j}}^{\mathbf{EM}}\) is the energy of interface interaction, computed as the sum of all contributions for all contacts between chain \(A_{i}\) and \(A_{j}\). \(<\mathbf{k}_{A_{i}A_{j}}^{\mathbf{EM}}\)\(>\) is the average value of the interaction energy. \(H\) is the label for heavy chain of FVIII, \(L\) is the label for light chain of FVIII, and \(V\) is the label for VWF. In the VWF/FL-FVIII complex, the VWF interacts with B domain in the heavy chain of FVIII. Figure 5: **VWF/FL-FVIII complex allosteric residues. ** Participation coefficient \(P\) heat map in color scale (blue to red, increasing values of \(P\)). Blue residues have a \(P=0\). Capital letters refer to protein domains of FVIII. The few allosteric residues (high \(P\) values) in the FL-FVIII/VWF complex (Figure 5) are localized at domain-B/VWF interface, domain B, and A3-C1 interface. The main difference between VWF/BDD-FVIII (Figure 6) and \(\rm\tilde{e}\)fanesococog alfa (Figure 7) stands in the localization and number of allosteric residues. Particularly in VWF/BDD-FVIII  
Figure 7: **Efanesococog alfa allosteric residues.