Revealing the Structural Basis of Promiscuous Amine Transaminase Activity

One lock for different keys: A flexible arginine in the active site allows γ-aminobutyrate:pyruvate transaminases to bind the chemically different substrates L-alanine and γ-aminobutyric acid. Moreover, a flexible arginine residue facilitates the promiscuous conversion of (S)-amines and ketones. The degree of promiscuity can be related to distinct key amino acids lying at the surface of the active site.