- Substrate-Tuned Catalysis of the Radical S-Adenosyl- L -Methionine Enzyme NosL Involved in Nosiheptide Biosynthesis
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NosL is a radical S-adenosyl-L-methionine (SAM) enzyme that converts L-Trp to 3-methyl-2-indolic acid, a key intermediate in the biosynthesis of a thiopeptide antibiotic nosiheptide. In this work we investigated NosL catalysis by using a series of Trp analogues as the molecular probes. Using a benzofuran substrate 2-amino-3-(benzofuran-3-yl)propanoic acid (ABPA), we clearly demonstrated that the 5′-deoxyadenosyl (dAdo) radical-mediated hydrogen abstraction in NosL catalysis is not from the indole nitrogen but likely from the amino group of L-Trp. Unexpectedly, the major product of ABPA is a decarboxylated compound, indicating that NosL was transformed to a novel decarboxylase by an unnatural substrate. Furthermore, we showed that, for the first time to our knowledge, the dAdo radical-mediated hydrogen abstraction can occur from an alcohol hydroxy group. Our study demonstrates the intriguing promiscuity of NosL catalysis and highlights the potential of engineering radical SAM enzymes for novel activities.
- Ji, Xinjian,Li, Yongzhen,Ding, Wei,Zhang, Qi
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p. 9021 - 9024
(2015/08/03)
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- Benzofuran Derivatives. Part 4. Synthesis of Benzofurans and 2,3,4,5-Tetrahydro-1-benzoxepin-3,5-diones
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By treatment of ethyl 4- or 5-substituted 2-acetylphenoxyacetates 1 with potassium hydroxide in dry dioxane, benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 were obtained.The relative yields of benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 varied with the types of 4- or 5-substituents.The electron-donating 4-methoxyl group favored the formation of benzoxepins.On the other hand, electron-withdrawing substituents such as the 4-nitro group favored the formation of benzofurans.When esters 1 were treated with sodium amide,2,3-dihydrobenzofurans 2 were obtained exclusively regardless of 4- or 5-substituents.
- Suzuki, Tsuneo,Tanemura, Kiyoshi,Horaguchi, Takaaki,Shimimizu, Takahachi,Sakakibara, Tohru
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p. 423 - 429
(2007/10/02)
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- BENZOFURAN DERIVATIVES. I. ON THE EFFECTS OF SUBSTITUENTS IN BENZOFURAN SYNTHESES.
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The Roessing's reaction of 4-substituted 2-acylphenoxyacetic acids give a mixture of benzofurans and 2-benzofurancarboxylic acids. The relative yields of benzofurans and 2-benzofurancarboxylic acids depend on the substituents on the benzene ring of the 2-acylphenoxyacetic acids. Electron-withdrawing substituents such as nitro groups favor the formation of 2-benzofurancarboxylic acids. On the other hand, the formation of benzofurans is favored by the steric hindrance of 2-acyl groups in the reaction of 2-acyl-4-nitrophenoxyacetic acids with anhydrous sodium acetate and acetic anhydride.
- Suzuki,Horaguchi,Shimizu,Abe
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p. 2762 - 2767
(2007/10/02)
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