3.3 A tie between hydrophobic interactions and hydrogen bonds:
permanent and transient domains
It is clear from the previous analysis that permanent domains have a
larger number of interactions between interacting domains than transient
domains. To obtain a clearer perspective on the interactions, we probed
atomic interactions of interfacial residues. We observed around 52% of
the total number of interactions in the case of proteins having
permanent domains are hydrophobic (Figure 3A). On the contrary, as shown
in Figure 3B, transient domains have only 37% of hydrophobic
interactions. These hydrophobic interactions are known to drive
different PPIs and are known to comprise major interactions in the
biomolecules which stabilize interacting complexes. Moreover, we found
that transient domains have large proportions of side chain associated
hydrogen bonds in comparison to permanent domains (Figure 3A, 3B and
Supplementary Figure S1), and such polar interactions are known to bring
out specificity. Apart from hydrophobic interactions and side chain
associated hydrogen bonds, all other interaction types were similarly
populated in the interface, which would be required for sustained domain
interactions and the functioning of multi-domain proteins.