(S)-PFI-2 hydrochloride is an inhibitor of lysine methyltransferase SETD7 and is approximately 500-fold more active than its enantiomer (R)-PFI-2. (R)-PFI-2 is a cofactor-dependent and substrate-competitive inhibitor. (R)-PFI-2 can occupy the substrate peptide binding groove of SETD7 (including the catalytic lysine binding channel) and interact with the cofactor The donor methyl group is in direct contact. However, (S)-PFI-2 was not observed to have the same interaction as (R)-PFI-2^[1][2].