Description_x000D_ General description_x000D_ IDO1 is a heme-enzyme that is induced by INF-γ and catalyzes the conversion of tryptophan to kynurenine. This leads to a depletion of tryptophan that results in T cells and dendritic cells inactivation. IDO activity has been identified as an important immune effector pathway in tumor cells to escape a potentially effective immune response. Inhibition of IDO1 has been found to delay cancer growth and enhance dendritic vaccines. Therapeutic inhibition of IDO1 is of interest because of its proposed role in the pathogenesis of several diseases, including cancer, hypotension, neurodegenerative disorders, and its potential to aid cancer immunotherapy and organ transplant._x000D_ Unit Definition_x000D_ One unit of enzyme hydrolyzes 1.0 pmole of L-Tryptophan to N-formyl-Lkynurenine per minute at pH-6.5 at 37°C