TRYPTOPHAN CATABOLISM IN BACILLUS-MEGATERIUM
TRYPTOPHAN CATABOLISM IN BACILLUS-MEGATERIUM
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DOI：
10.1128/jb.121.1.70-76.1975
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发表时间：
1975-01-01
影响因子：
3.2
通讯作者：
SADOFF, HL
中科院分区：
文献类型：
--
作者：
BOUKNIGHT, RR;SADOFF, HL
巨大芽孢杆菌在含有L-色氨酸作为唯一碳、氮和能量来源的培养基中生长。犬尿氨酸、邻氨基苯甲酸和邻苯二酚是代谢中间体，表明该生物体使用邻氨基苯甲酸途径降解色氨酸。在L-色氨酸上生长的细胞氧化犬尿氨酸、丙氨酸和邻氨基苯甲酸，细胞提取物中色氨酸加氧酶（EC 1.13.1.12）、犬尿氨酸酶（EC 3.7.1.3）和儿茶酚加氧酶（EC 1.13.1.1）的存在为B中的降解途径提供了额外的证据。巨大的色氨酸加氧酶被叠氮化钠、氰化钾和羟胺抑制，表明该酶具有功能性血红素基团。D-色氨酸不是色氨酸加氧酶的底物，D-异构体不抑制这种酶。提取物中未检出甲酰胺酶（EC 3.5.1.9）和邻氨基苯甲酸羟化酶。色氨酸催化剂在B megaterium中是可诱导的，并且受到葡萄糖和谷氨酸的分解代谢物阻遏。精氨酸不引起阻遏，犬尿氨酸诱导色氨酸加氧酶和犬尿氨酸酶。
Bacillus megaterium grows in a medium containing L-tryptophan as the sole carbon, nitrogen, and energy source. Kynurenine, anthranilic acid, and catechol are metabolic intermediates, suggesting that this organism used the anthranilic acid pathway for tryptophan degradation. Cells that grow on L-tryptophan oxidize kynurenine, alanine, and anthranilic acid and the presence of tryptophan oxygenase (EC 1.13.1.12), kynureninase (EC 3.7.1.3), and catechol oxygenase (EC 1.13.1.1) in cell extracts provide additional evidence for the degradative pathway in B. megaterium. Tryptophan oxygenase is inhibited by sodium azide, potassium cyanide, and hydroxylamine, indicating that the enzyme has a functional heme group. D-Tryptophan is not a substrate for tryptophan oxygenase, and the D-isomer does not inhibit this enzyme. Formamidase (EC 3.5.1.9) and anthranilate hydroxylase are not detectable in extracts. Tryptophan catabolism is inducible in B megaterium and is subject to catabolite repression by glucose and glutamate. Arginine does not cause repression, and kynurenine induces both tryptophan oxygenase and kynureninase.