Purity ~90% (SDSPAGE). Kynurenine aminotransferase II (KATII), also known as alphaAminoadipate Aminotransferase (AADAT), catalyzes the PLPdependent transamination of aminoadipate to alphaoxoadipate in the catabolism of lysine in the liver and also is the primary brain enzyme catalyzing the transamination of kynurenine to kynurenic acid (KYNA) (1). KYNA is an endogenous antagonist of the NmethylDaspartate (NMDA) receptors with weaker effects on kainite and alphaamino3hydroxy5 methyl4isoxazole (AMPA) receptors, the other two ionotropic glutamate receptors (2, 3). KYNA also acts upon alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) and importantly may suppress the presynaptic release of glutamate to confer neuroprotective effects against NMDAreceptor mediated overstimulation. Also, KYNA is an endogenous ligand of the orphaned G proteincoupled receptor 35 (GPR35), found primarily in immune cells, and may induce inositol phosphate production and Ca2+ mobilizaiton