CCBL1 is a cytosolic enzyme which is responsible for the metabolism of cysteine conjugates of certain halogenated alkenes and alkanes. This metabolism leads to the formation of reactive metabolites which can lead to nephrotoxicity and neurotoxicity.
CCBL1 catalyzes the irreversible transamination of the L-tryptophan metabolite L-kinurenine to form kynurenic acid (KA). It catalyzes the beta-elimination of S-conjugates and Se-conjugates of L-(seleno)cysteine, resulting in the cleavage of the C-S or C-Se bond.
This enzyme has a central role in the bioactivation of nephrotoxic halogenated hydrocarbons - the possibility of human exposure to these chemicals has focused interest on the CCBL1 from human kidney.