title: Purification and characterization of a cysteine dioxygenase from the yeast phase of Histoplasma capsulatum.
abstract: A cysteine dioxygenase, cysteine oxidase (EC 1.13.11.20), has been purified from the cytosolic fraction of yeast phase cells of the dimorphic fungus Histoplasma capsulatum. The cysteine oxidase is an iron-containing dioxygenase with a molecular weight of 10500 (+/- 1500) and is present only in the yeast phase of the fungus. The enzyme is highly specific for L-cysteine, with a Km of 2 X 10(-5) M in vitro. The product of cysteine oxidation is cysteinesulfinic acid, as analyzed by thin-layer chromatography and mass spectroscopy. To our knowledge, this is the first cysteine oxidase isolated from a fungus, and it probably plays an important role in the mycelial to yeast phase transition of H. capsulatum during which redox potential and cysteine levels are crucial factors.
mesh_terms: D050558:Cysteine Dioxygenase; D049308:Dioxygenases; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis; D006658:Histoplasma / Q000201:enzymology*; D010105:Oxygenases / Q000302:isolation & purification* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D013379:Substrate Specificity
chemical_list: D010446:Peptide Fragments; D005182:Flavin-Adenine Dinucleotide; D010105:Oxygenases; D049308:Dioxygenases; D050558:Cysteine Dioxygenase