Tryptophan synthase beta chain (TrpB)

The tryptophan synthase beta chain (TrpB) is an enzyme subunit that catalyzes the last step in the biosynthesis of L-tryptophan, converting indole and L-serine into L-tryptophan in a reaction requiring the cofactor pyridoxal phosphate[3][4][5][6][7][8]. This subunit forms part of the tryptophan synthase complex, which typically operates as an α₂β₂ tetramer in bacteria and other non-mammalian organisms. The beta chain (TrpB) is responsible for the beta elimination and subsequent condensation of indole with L-serine. TrpB is found in bacteria, archaea, fungi, and plants, but not in animals, as the latter acquire tryptophan through diet. The enzyme's beta chain exists in at least two phylogenetically distinct subgroups (TrpEb_1 and TrpEb_2), and in certain Archaea, the minor group (TrpEb_2) may additionally catalyze L-serine deamination[2]. TrpB requires pyridoxal-phosphate (PLP) as a cofactor, which is covalently attached to a lysine residue within the active site[5][6]. Caveats: There is no evidence for a role in human disease as a direct target, and it is not clinically targeted by approved therapies; however, it is a validated enzymatic step in the microbial syntheses of tryptophan and thus has potential in antibacterial drug discovery[2][3].

Other names

Tryptophan synthase TrpBTrpBTryptophan synthase beta subunitTryptophan synthase subunit beta

No drugs in clinical use; in research, inhibitors would likely act via competitive or allosteric inhibition of enzymatic function.