Studying protein-peptide interactions using benzophenone units: A case study of protein kinase B/Akt and its inhibitor PTR6154

Protein-protein interactions (PPIs) govern nearly all processes in living cells. Peptides play an important role in studying PPIs. Peptides carrying photoaffinity labels that covalently bind the interacting protein can be used to obtain more accurate information regarding PPIs. Benzophenone (BP) is a useful photoaffinity label that is widely used to study PPIs. We developed a one-pot two-step synthesis for the preparation of novel BP units. To map the binding site more thoroughly, linkers of various lengths were attached to the BP moiety. These units can be incorporated into peptide sequences using well-established solid phase peptide synthesis (SPPS) protocols. As a proof of concept, we studied the interaction between protein kinase B (PKB/Akt) and its synthetic peptide inhibitor, PTR6154. The methodology is general and can be implemented to study PPIs in a variety of biological systems.