title: Human indolylamine 2,3-dioxygenase. Its tissue distribution, and characterization of the placental enzyme.
abstract: The presence of indolylamine 2,3-dioxygenase was examined in human subjects by determining its activity with L-tryptophan as substrate. Enzyme activity was detected in various tissues, and was relatively high in the lung, small intestine and placenta. Human indolylamine 2,3-dioxygenase, partially purified from the placenta, had an Mr of about 40 000 by gel filtration and exhibited a single pI of 6.9. The human enzyme required a reducing system, ascorbic acid and Methylene Blue, for maximal activity and was able to oxidize D-tryptophan, 5-hydroxy-L-tryptophan as well as L-tryptophan, but kinetic studies indicated that the best substrate of the enzyme was L-tryptophan.
mesh_terms: D005260:Female; D006801:Humans; D007700:Kinetics; D010105:Oxygenases / Q000302:isolation & purification / Q000378:metabolism*; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D014018:Tissue Distribution; D014364:Tryptophan / Q000378:metabolism; D014366:Tryptophan Oxygenase
chemical_list: D014364:Tryptophan; D010105:Oxygenases; D014366:Tryptophan Oxygenase