33468-35-8

Usage

Uses

Different sources of media describe the Uses of 33468-35-8 differently. You can refer to the following data:
1. The natural enantiomer of Chlorotryptophan
2. The natural enantiomer of Chlorotryptophan.

Upstream product

• 220906-11-6 (2R,5S)-3,6-diethoxy-2-isopropyl-5-[3-(triethylsilyl)prop-2-ynyl]-2,5-dihydropyrazine 
• 17422-33-2 6-chloroindole 
• 56-45-1 L-serin 
• 50517-10-7 N^α-acetyl-6-chloro-D,L-tryptophan 
• 73-22-3 L-Tryptophan 
• 441801-03-2 6-chloro-3-methylindole-2-carboxylate 
• 158905-35-2 6-chloro-3-methyl-1H-indole 
• 769973-16-2 6-chloro-L-tryptophan ethyl ester 
• 808145-70-2 6-Chloro-3-((2S,5R)-3,6-diethoxy-5-isopropyl-2,5-dihydro-pyrazin-2-ylmethyl)-2-triethylsilanyl-1H-indole 
• 89-63-4 4-Chloro-2-nitroaniline 
• 6828-35-9 5-chloro-2-iodoaniline 
• 5446-05-9 4-chloro-2-nitroiodobenzene 
• 769973-15-1 (3S,6R)-3-[[1-(tert-butyloxycarbonyl)-6-chloro-3-indolyl]methyl]-3,6-dihydro-6-isopropyl-2,5-diethoxypyrazine 
• 1027297-43-3 tert-butyl 3-(bromomethyl)-6-chloro-1H-indole-1-carboxylate 

Downstream Products

• 1028302-45-5 N-trityl-6-chloro-L-tryptophan 
• 908847-42-7 (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(6-chloro-1H-indol-3-yl)propanoic acid 
• 1217738-82-3 (S)-N-boc-6-chloro-tryptophan 
• 3670-19-7 2-(6-chloro-1H-indole-3-yl)ethan-1-amine 
• 175777-22-7 L-4-chlorokynurenine 
• 769973-17-3 N-trityl-6-chloro-L-tryptophan tert-butyl ester 

Relevant academic research and scientific papers

Targeted Enzyme Engineering Unveiled Unexpected Patterns of Halogenase Stabilization

Halogenases are valuable biocatalysts for selective C?H activation, but despite recent efforts to broaden their application scope by means of protein engineering, improvement of thermostability and catalytic efficiency is still desired. A directed evoluti

Biosynthesis of l-4-Chlorokynurenine, an Antidepressant Prodrug and a Non-Proteinogenic Amino Acid Found in Lipopeptide Antibiotics

l-4-Chlorokynurenine (l-4-Cl-Kyn) is a neuropharmaceutical drug candidate that is in development for the treatment of major depressive disorder. Recently, this amino acid was naturally found as a residue in the lipopeptide antibiotic taromycin. Herein, we report the unprecedented conversion of l-tryptophan into l-4-Cl-Kyn catalyzed by four enzymes in the taromycin biosynthetic pathway from the marine bacterium Saccharomonospora sp. CNQ-490. We used genetic, biochemical, structural, and analytical techniques to establish l-4-Cl-Kyn biosynthesis, which is initiated by the flavin-dependent tryptophan chlorinase Tar14 and its flavin reductase partner Tar15. This work revealed the first tryptophan 2,3-dioxygenase (Tar13) and kynurenine formamidase (Tar16) enzymes that are selective for chlorinated substrates. The substrate scope of Tar13, Tar14, and Tar16 was examined and revealed intriguing promiscuity, thereby opening doors for the targeted engineering of these enzymes as useful biocatalysts.

Structure-based switch of regioselectivity in the flavin-dependent tryptophan 6-halogenase Thal

Flavin-dependent halogenases increasingly attract attention as biocatalysts in organic synthesis, facilitating environmentally friendly halogenation strategies that require only FADH2, oxygen, and halide salts. Different flavin-dependent tryptophan halogenases regioselectively chlorinate or brominate tryptophan’s indole moiety at C5, C6, or C7. Here, we present the first substrate-bound structure of a tryptophan 6-halogenase, namely Thal, also known as ThdH, from the bacterium Streptomyces albogriseolus at 2.55 ? resolution. The structure revealed that the C6 of tryptophan is positioned next to the -amino group of a conserved lysine, confirming the hypothesis that proximity to the catalytic residue determines the site of electro-philic aromatic substitution. Although Thal is more similar in sequence and structure to the tryptophan 7-halogenase RebH than to the tryptophan 5-halogenase PyrH, the indole binding pose in the Thal active site more closely resembled that of PyrH than that of RebH. The difference in indole orientation between Thal and RebH appeared to be largely governed by residues positioning the Trp backbone atoms. The sequences of Thal and RebH lining the substrate binding site differ in only few residues. Therefore, we exchanged five amino acids in the Thal active site with the corresponding counterparts in RebH, generating the quintuple variant Thal-RebH5. Overall conversion of L-Trp by the Thal-RebH5 variant resembled that of WT Thal, but its regioselectivity of chlorination and bromination was almost completely switched from C6 to C7 as in RebH. We conclude that structure-based protein engineering with targeted substitution of a few residues is an efficient approach to tailoring flavin-dependent halogenases.

An Unusual Flavin-Dependent Halogenase from the Metagenome of the Marine Sponge Theonella swinhoei WA

Uncultured bacteria from sponges have been demonstrated to be responsible for the generation of many potent, bioactive natural products including halogenated metabolites.1 The identification of gene clusters from the metagenomes of such bacterial communities enables the discovery of enzymes that mediate new and useful chemistries and allows insight to be gained into the biogenesis of potentially pharmacologically important natural products. Here we report a new pathway to the keramamides (krm); the first functional evidence for the existence of a distinct producer in the Theonella swinhoei WA chemotype is revealed, and a key enzyme on the pathway, a unique flavin-dependent halogenase with a broad substrate specificity, with potential as a useful new biocatalytic tool, is described.

Unlocking Reactivity of TrpB: A General Biocatalytic Platform for Synthesis of Tryptophan Analogues

Derivatives of the amino acid tryptophan (Trp) serve as precursors for the chemical and biological synthesis of complex molecules with a wide range of biological properties. Trp analogues are also valuable as building blocks for medicinal chemistry and as tools for chemical biology. While the enantioselective synthesis of Trp analogues is often lengthy and requires the use of protecting groups, enzymes have the potential to synthesize such products in fewer steps and with the pristine chemo- and stereoselectivity that is a hallmark of biocatalysis. The enzyme TrpB is especially attractive because it can form Trp analogues directly from serine (Ser) and the corresponding indole analogue. However, many potentially useful substrates, including bulky or electron-deficient indoles, are poorly accepted. We have applied directed evolution to TrpB from Pyrococcus furiosus and Thermotoga maritima to generate a suite of catalysts for the synthesis of previously intractable Trp analogues. For the most challenging substrates, such as nitroindoles, the key to improving activity lay in the mutation of a universally conserved and mechanistically important residue, E104. The new catalysts express at high levels (>200 mg/L of Escherichia coli culture) and can be purified by heat treatment; they can operate up to 75 °C (where solubility is enhanced) and can synthesize enantiopure Trp analogues substituted at the 4-, 5-, 6-, and 7-positions, using Ser and readily available indole analogues as starting materials. Spectroscopic analysis shows that many of the activating mutations suppress the decomposition of the active electrophilic intermediate, an amino-acrylate, which AIDS in unlocking the synthetic potential of TrpB.

A Structure-Guided Switch in the Regioselectivity of a Tryptophan Halogenase

Flavin-dependent halogenases are potentially useful biocatalysts for the regioselective halogenation of aromatic compounds. Haloaromatic compounds can be utilised in the synthesis and biosynthesis of pharmaceuticals and other valuable products. Here we report the first X-ray crystal structure of a tryptophan 6-halogenase (SttH), which enabled key residues that contribute to the regioselectivity in tryptophan halogenases to be identified. Structure-guided mutagenesis resulted in a triple mutant (L460F/P461E/P462T) that exhibited a complete switch in regioselectivity; with the substrate 3-indolepropionate 75 % 5-chlorination was observed with the mutant in comparison to 90 % 6-chlorination for the wild-type SttH. This is the first clear example of how regiocomplementary halogenases can be created from a single parent enzyme. The biocatalytic repertoire of SttH was also expanded to include a range of indolic and non-indolic substrates.

Structure and biocatalytic scope of thermophilic flavin-dependent halogenase and flavin reductase enzymes

Flavin-dependent halogenase (Fl-Hal) enzymes have been shown to halogenate a range of synthetic as well as natural aromatic compounds. The exquisite regioselectively of Fl-Hal enzymes can provide halogenated building blocks which are inaccessible using standard halogenation chemistries. Consequently, Fl-Hal are potentially useful biocatalysts for the chemoenzymatic synthesis of pharmaceuticals and other valuable products, which are derived from haloaromatic precursors. However, the application of Fl-Hal enzymes, in vitro, has been hampered by their poor catalytic activity and lack of stability. To overcome these issues, we identified a thermophilic tryptophan halogenase (Th-Hal), which has significantly improved catalytic activity and stability, compared with other Fl-Hal characterised to date. When used in combination with a thermostable flavin reductase, Th-Hal can efficiently halogenate a number of aromatic substrates. X-ray crystal structures of Th-Hal, and the reductase partner (Th-Fre), provide insights into the factors that contribute to enzyme stability, which could guide the discovery and engineering of more robust and productive halogenase biocatalysts.

MACROCYCLIC PEPTIDOMIMETICS FOR ALPHA-HELIX MIMICRY

Methods and compositions are provided for generating macrocyclic peptides constrained by side-chain-to-C-terminus non-peptidic tethers for use as functional and structural mimics of α-helical motifs, including in therapeutic applications. These methods can be used to produce libraries of conformationally constrained peptidomimetics to identify compounds with desired activity properties.

Synthesis of tripeptides containing d-Trp substituted at the indole ring, assessment of opioid receptor binding and in vivo central antinociception

The noncationizable tripeptide Ac-d-Trp-Phe-GlyNH2 was recently proposed as a novel minimal recognition motif for μ-opioid receptor. The introduction of different substituents (methyl, halogens, nitro, etc.) at the indole of d-Trp significantly influenced receptor affinities and resulted in serum stability and in a measurable effect on central antinociception in mice after ip administration.

An expression system for the efficient incorporation of an expanded set of tryptophan analogues

Biosynthetic incorporation of tryptophan (Trp) analogues in recombinant proteins using an E. coli Trp auxotroph expression host is limited to analogues modified with a small substituent like a fluoro atom or a hydroxyl or amine group. We report here the e