- Cloning and characterization of indolepyruvate decarboxylase from Methylobacterium extorquens AM1
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For the first time for methylotrophic bacteria an enzyme of phytohormone indole-3-acetic acid (IAA) biosynthesis, indole-3-pyruvate decarboxylase (EC 4.1.1.74), has been found. An open reading frame (ORF) was identified in the genome of facultative methylotroph Methylobacterium extorquens AM1 using BLAST. This ORF encodes thiamine diphosphate-dependent 2-keto acid decarboxylase and has similarity with indole-3-pyruvate decarboxylases, which are key enzymes of IAA biosynthesis. The ORF of the gene, named ipdC, was cloned into overexpression vector pET-22b(+). Recombinant enzyme IpdC was purified from Escherichia coli BL21(DE3) and characterized. The enzyme showed the highest k cat value for benzoylformate, albeit the indolepyruvate was decarboxylated with the highest catalytic efficiency (k cat/K m). The molecular mass of the holoenzyme determined using gel-permeation chromatography corresponds to a 245-kDa homotetramer. An ipdC-knockout mutant of M. extorquens grown in the presence of tryptophan had decreased IAA level (46% of wild type strain). Complementation of the mutation resulted in 6.3-fold increase of IAA concentration in the culture medium compared to that of the mutant strain. Thus involvement of IpdC in IAA biosynthesis in M. extorquens was shown.
- Fedorov,Doronina,Trotsenko
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- Synthesis of Weinreb amides using diboronic acid anhydride-catalyzed dehydrative amidation of carboxylic acids
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The first successful example of the direct synthesis of Weinreb amides using catalytic hydroxy-directed dehydrative amidation of carboxylic acids using the diboronic acid anhydride catalyst is described. The methodology is applicable to the concise syntheses of eight α-hydroxyketone natural products, namely, sattabacin, 4-hydroxy sattabacin, kurasoins A and B, soraphinols A and B, and circumcins B and C.
- Shimada, Naoyuki,Takahashi, Naoya,Ohse, Naoki,Koshizuka, Masayoshi,Makino, Kazuishi
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supporting information
p. 13145 - 13148
(2020/11/09)
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- Stepwise O-Atom Transfer in Heme-Based Tryptophan Dioxygenase: Role of Substrate Ammonium in Epoxide Ring Opening
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Heme-based tryptophan dioxygenases are established immunosuppressive metalloproteins with significant biomedical interest. Here, we synthesized two mechanistic probes to specifically test if the α-amino group of the substrate directly participates in a critical step of the O atom transfer during catalysis in human tryptophan 2,3-dioxygenase (TDO). Substitution of the nitrogen atom of the substrate to a carbon (probe 1) or oxygen (probe 2) slowed the catalytic step following the first O atom transfer such that transferring the second O atom becomes less likely to occur, although the dioxygenated products were observed with both probes. A monooxygenated product was also produced from probe 2 in a significant quantity. Analysis of this new product by HPLC coupled UV-vis spectroscopy, high-resolution mass spectrometry, 1H NMR, 13C NMR, HSQC, HMBC, and infrared (IR) spectroscopies concluded that this monooxygenated product is a furoindoline compound derived from an unstable epoxyindole intermediate. These results prove that small molecules can manipulate the stepwise O atom transfer reaction of TDO and provide a showcase for a tunable mechanism by synthetic compounds. The product analysis results corroborate the presence of a substrate-based epoxyindole intermediate during catalysis and provide the first substantial experimental evidence for the involvement of the substrate α-amino group in the epoxide ring-opening step during catalysis. This combined synthetic, biochemical, and biophysical study establishes the catalytic role of the α-amino group of the substrate during the O atom transfer reactions and thus represents a substantial advance to the mechanistic comprehension of the heme-based tryptophan dioxygenases.
- Shin, Inchul,Ambler, Brett R.,Wherritt, Daniel,Griffith, Wendell P.,Maldonado, Amanda C.,Altman, Ryan A.,Liu, Aimin
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supporting information
p. 4372 - 4379
(2018/04/05)
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- Biocontrolled formal inversion or retention of L -α-amino acids to enantiopure (R)- or (S)-hydroxyacids
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Natural L-α-amino acids and L-norleucine were transformed to the corresponding α-hydroxy acids by formal biocatalytic inversion or retention of absolute configuration. The one-pot transformation was achieved by a concurrent oxidation reduction cascade in aqueous media. A representative panel of enantiopure (R)- and (S)-2-hydroxy acids possessing aliphatic, aromatic and heteroaromatic moieties were isolated in high yield (67-85 %) and enantiopure form (>99 % ee) without requiring chromatographic purification.
- Busto, Eduardo,Grischek, Barbara,Kroutil, Wolfgang,Richter, Nina
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supporting information
p. 11225 - 11228,4
(2015/01/07)
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- Structure and enantioselective synthesis of polyamine toxin MG30 from the venom of the spider Macrothele gigas
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A novel polyamine toxin, named MG30, was isolated from the venom of the spider, Macrothele gigas, and its structure was elucidated by two-dimensional NMR and mass analysis. In addition, the enantioselective synthesis of MG30 was achieved to assign its absolute stereochemistry.
- Yamaji, Nahoko,Horikawa, Manabu,Corzo, Gerardo,Naoki, Hideo,Haupt, Joachim,Nakajima, Terumi,Iwashita, Takashi
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p. 5371 - 5373
(2007/10/03)
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- Synthesis of All Nineteen Appropriately Protected Chiral α-Hydroxy Acid Equivalents of the α-Amino Acids for Boc Solid-Phase Depsi-Peptide Synthesis
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(Equation presented) The preparation of depsi-peptides, amide-to-ester-substituted peptides used to probe the role of hydrogen bonding in protein folding energetics, is accomplished by replacing specific L-α-amino acid residues by their α-hydroxy acid cou
- Deechongkit, Songpon,You, Shu-Li,Kelly, Jeffery W.
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p. 497 - 500
(2007/10/03)
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- Tryptophan-derived NK1 antagonists: Conformationally constrained heterocyclic bioisosteres of the ester linkage
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The 3,5-bis(trifluoromethyl)benzyl ester of N-acetyl-L-tryptophan 1 (L- 732,138) has been identified previously as a potent and selective substance P receptor antagonist. A series of analogs which introduced a 6-membered heterocyclic ring into the backbon
- Lewis,MacLeod,Merchant,Kelleher,Sanderson,Herbert,Cascieri,Sadowski,Ball,Hoogsteen
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p. 923 - 933
(2007/10/02)
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- Formations of (5-Hydroxy)indole S-(-)-lactic Acid, N-acetyl-5-hydroxy-L-tryptophan and (5-Hydroxy)indole Carboxylic Acid in the Metabolism of Tryptophan and 5-Hydroxytryptophan by Chromobacterium violaceum
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Tryptophan metabolism catalyzing the production of (5-hydroxy)indolelactate, (5-hydroxy)indole carboxylate, and N-acetyl-5-hydroxytryptophan was found in Chromobacterium violaceum.These metabolites have never been reported before.Metabolic pathways from tryptophan and 5-hydroxytryptophan are proposed.
- Hoshino, Tsutomu,Yamamoto, Masahiro,Uchiyama, Takeo
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p. 1609 - 1610
(2007/10/02)
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