BQ-123

BQ-123 is a cyclic peptide consisting of five amino acids. The amino acid sequence is D-tryptamine-D-aspartic acid-L-proline-D-valine-L-leucine. BQ-123 is a cyclic peptide consisting of five amino acids. The amino acid sequence is D-tryptamine-D-aspartic acid-L-proline-D-valine-L-leucine. BQ-123 is a selective ETA endothelin receptor antagonist. As such, it is used as a biochemical tool in the study of endothelin receptor function. BQ-123 works as an ET-1 antagonist by reversing already established contractions to ET-1. This indicates that BQ-123 can work as an antagonist to remove ET-1 from its receptor (ETA).