PADs 1, 2, 3 and 4 were purified as reported.44 (link), 53 (link) Rhodamine-phenylglyoxal (Rh-PG) was synthesized as reported.43 (link) The plasmid pET28a-LIC, harboring the NNMT gene was purchased from Addgene (Addgene plasmid # 40734). All chemicals were purchased from Sigma.