Tryptophan 2,3-dioxygenase in Saccharomyces cerevisiae.
The tryptophan pyrrole-ring cleavage enzyme (TPCE) was detected in the yeast Saccharomyces cerevisiae. TPCE activity existed constitutively and was markedly induced by culturing the cells in a medium containing 0.1% (w/v) L-tryptophan. We purified partially the enzyme from the L-tryptophan-induced cells by phospho-cellulose column chromatography. The partially purified enzyme was stimulated solely by L-ascorbic acid, a nonspecific reductant, suggesting that the yeast TPCE is not indoleamine 2,3-dioxygenase, but rather tryptophan 2,3-dioxygenase. The enzyme metabolized L-tryptophan preferentially, and D-tryptophan slightly. KCN and NaN3, exogenous ligands of heme, inhibited the enzyme activity drastically, indicating that yeast tryptophan 2,3-dioxygenase contains heme(s) in its active site. The optimal pH of the enzyme was 6.5. Upon two-dimensional polyacrylamide gel electrophoresis, a protein staining spot was identified that was induced by L-tryptophan and whose intensity changed in correlation with the tryptophan 2,3-dioxygenase activity after phospho-cellulose column chromatography. This protein, exhibiting a molecular weight of approximately 38,000 and an isoelectric point of approximately pH 8.0, may be identified as a subunit of yeast tryptophan 2,3-dioxygenase.
Iwamoto
Y
Y
Department of Biochemistry, Wakayama Medical College, Japan.
Lee
I S
IS
Tsubaki
M
M
Kido
R
R
D001386:Azides / Q000494:pharmacology; D001665:Binding Sites; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D005656:Fungal Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D006418:Heme / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007737:Kynurenine / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D019810:Sodium Azide; D013379:Substrate Specificity; D014364:Tryptophan / Q000378:metabolism; D014366:Tryptophan Oxygenase / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000302:isolation & purification
D001386:Azides; D005656:Fungal Proteins; D007737:Kynurenine; D006418:Heme; D014364:Tryptophan; D019810:Sodium Azide; D014366:Tryptophan Oxygenase; D011190:Potassium Cyanide