Kinetic Target-Guided Synthesis of ERAP2 Inhibitors

Key words

ERAP2 inhibitors - kinetic target-guided synthesis - triazoles

Significance

Endoplasmic reticulum aminopeptidase 2 (ERAP2) is involved in the trimming of antigenic peptides and modulates the immunopeptidome presented at the cell surface by major histocompatibility complex class I. It is a target for the treatment of autoimmune disease and in cancer immunotherapy. Previously developed ERAP 2 inhibitors lacked selectivity over related enzymes such as insulin-regulated aminopeptidase (IRAP) or displayed low potency. In the highlighted article, the authors used kinetic target-guided synthesis (KTGS) to develop the first nanomolar and selective ERAP2 inhibitors. In KTGS, the protein serves as a template for an equilibrium-controlled selection of alkynes and azides. The fragments that fit best to the binding site are linked by a (3+2)-cycloaddition to form triazole ligands. This method can be used to identify inhibitors that bind to previously unknown protein conformations by utilizing the flexibility of the target.

Comment

Six azides were incubated with mixtures of alkynes in the presence and absence of ERAP2. Mass spectrometry was used to assess the selectivity of the protein-templated triazole formation. This resulted in the identification of 19 hit compounds out of 1050 possible combinations. The selection was further narrowed to 6 compounds, of which compound A was the most potent. The structure was then optimized for potency and selectivity over IRAP. Switching from a 1,5- to a 1,4-triazole core and shortening the hydroxamic acid tail (B) changed the binding mode and improved selectivity towards ERAP2. Exchanging the phenyl group for a 2-pyridyl group (C) and introduction of a methyl group on the phenolic hydroxy group resulted in a potent and selective inhibitor (D) of ERAP2 by improving interactions with non-conserved residues.

Publication History

Article published online:
18 October 2022