flavivirin flavivirin flavivirin (ec 3.4.21.91, yellow fever virus (flavivirus) protease, ns2b-3 proteinase) is an enzyme. flavivirinidentifiersec no.3.4.21.91cas no.154215-26-6 databasesintenzintenz viewbrendabrenda entryexpasynicezyme viewkeggkegg entrymetacycmetabolic pathwaypriamprofilepdb structuresrcsb pdb pdbe pdbsumsearchpmcarticlespubmedarticlesncbiproteins