How does thermodynamics relate to the study of protein-protein interactions in drug design? Since the late 1980s the problem of protein-protein interaction in drug design has been a topic of great interest. The problem generally arises for two reasons. First, many protein-protein interactions are based on direct interactions \[[@B26-proteomes-02-00173]\], in which aldimine formation reduces the affinities of dronedarone and sodium nitroprusside, while ammonium formation by the sodium nitroprusside prevents it. Second, the chemistry of the protein-protein interactions are based on the interaction between primary hydroxyl groups and peptides. They are in general formed by a mixture of free amines and their derivatives. Several peptides that were selected as interacting peptide in MD simulation recently have shown to include salt bridges between carbonylation groups of tyrosol derivative with 6-OH groups \[[@B27-proteomes-02-00173]\]. Thus it can be concluded that the molecules are quite good in terms of stability and specificity so that a reliable method for designing novel drugs is still desirable. Thus, the study of conformational properties of target peptides is important and valuable. In this review we will deal with protein–protein interaction properties in the context of drug design. Moreover, the future direction of rational design of drug interaction surfaces to establish active ingredients of prescribed use is also discussed. ![PCR (probe-on-chip) protocol for nucleic acid binding. The chip provides DNA probes for interacting with a target molecule \[[@B28-proteomes-02-00173]\], thereby rapidly and cost-effectively binding to the target molecule with maximum activity \[[@B29-proteomes-02-00173]\].](proteomes-02-00173-g001){#proteomes-02-00173-f001} 






