TRYPTOPHAN 2,3-DIOXYGENASE IN SACCHAROMYCES-CEREVISIAE

被引:16
作者
IWAMOTO, Y [1 ]
LEE, ISM [1 ]
TSUBAKI, M [1 ]
KIDO, R [1 ]
机构
[1] HIMEJI INST TECHNOL, FAC SCI, DEPT LIFE SCI, KAMIGORI, HYOGO 67812, JAPAN
关键词
TRYPTOPHAN 2,3-DIOXYGENASE; SACCHAROMYCES CEREVISIAE; PARTIAL PURIFICATION; HEME;
D O I
10.1139/m95-003
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
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.
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页码:19 / 26
页数:8
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