- Expressed Protein Ligation without Intein
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Proteins with a functionalized C-terminus such as a C-terminal thioester are key to the synthesis of larger proteins via expressed protein ligation. They are usually made by recombinant fusion to intein. Although powerful, the intein fusion approach suffe
- Kratch, Kaci C.,Leeuwon, Sunshine Z.,Liu, Wenshe Ray,Morse, Jared S.,Qiao, Yuchen,Wang, Wesley Wei,Wang, Xiaoyan Aria,Xu, Shiqing,Yu, Ge
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- 18F-Trifluoromethylation of Unmodified Peptides with 5-18F-(Trifluoromethyl)dibenzothiophenium Trifluoromethanesulfonate
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The 18F-labeling of 5-(trifluoromethyl)-dibenzothiophenium trifluoromethanesulfonate, commonly referred to as the Umemoto reagent, has been accomplished applying a halogen exchange 18F-fluorination with 18F-fluoride, follo
- Verhoog, Stefan,Kee, Choon Wee,Wang, Yanlan,Khotavivattana, Tanatorn,Wilson, Thomas C.,Kersemans, Veerle,Smart, Sean,Tredwell, Matthew,Davis, Benjamin G.,Gouverneur, Véronique
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supporting information
p. 1572 - 1575
(2018/02/17)
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- Electrophilic S-trifluoromethylation of cysteine side chains in α- and β-peptides: Isolation of trifluoromethylated sandostatin (octreotide) derivatives
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The new electrophilic trifluoromethylating 1-(trifluoromethyl)-benziodoxole reagents A and B (Scheme 1) have been used to selectively attach CF3 groups to the S-atom of cysteine side chains of α- and β-peptides (up to 13-residues-long; products 7-14). Other functional groups in the substrates (amino, amido, carbamate, carboxylate, hydroxy, phenyl) are not attacked by these soft reagents. Depending on the conditions, the indole ring of a Trp residue may also be trifluoromethylated (in the 2-position). The products are purified by chromatography, and identified by 1H-, 13C-, and 19F-NMR spectroscopy, by CD spectroscopy, and by high-resolution mass spectrometry. The CF3 groups, thus introduced, may be replaced by H (Na/NH3), an overall Cys/Ala conversion. The importance of trifluoromethylations in medicinal chemistry and possible applications of the method (spin-labelling, imaging, PET) are discussed.
- Caponea, Stefania,Kieltschb, Iris,Floegela, Oliver,Lelaisa, Gerald,Togni, Antonio,Seebach, Dieter
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experimental part
p. 2035 - 2056
(2009/02/08)
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- Design and synthesis of novel amino acid-bearing macrocyclic calix[4]arenes
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A new family of macrocyclic calix[4]arenes (4a-d) potentially capable of chiral recognition were synthesized by incorporating the chirality inducing moieties, bis α-amino acylated polyethylene glycols, or tripeptide bis-Phe Cystine(OMe)2 to the
- Zhang, GuoZhu,Li, ZuCheng,Wang, Min,He, JiaQi,Cheng, JinPei
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p. 3615 - 3621
(2007/10/03)
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- Cystinophanes, a novel family of aromatic-bridged cystine cyclic peptides: Synthesis, crystal structure, molecular recognition, and conformational studies
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A novel family of aromatic-bridged cystine cyclic peptides (cystinophanos) has been synthesized by a single-step procedure involving condensation of 1,3 aromatic (Ph or Pyr unit) dicarbonyl dichloride with either the simple L-cystine dimethyl ester to pro
- Ranganathan, Darshan,Haridas,Karle, Isabella L.
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p. 2695 - 2702
(2007/10/03)
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- Oxidative Deblocking of the 4-Methoxybenzyl Thioether Protecting Group: Application to the Directed Synthesis of Poly-cystinyl Peptides
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The 4-methoxybenzyl thioether protecting group is deblocked efficiently by oxidation with the homogeneous electron transfer agent tris(4-bromophenyl)ammoniumyl (2.+) leading to the disulfide in high yields.S-(4-methoxybenzyl)cysteine derivatives like 9 in this way can be transformed into the corresponding cystine derivatives like 10 in 90percent yield.Many N and carboxy protecting groups like the Boc and Z group and tert-butyl or benzyl ester functions are stable under the cleavage conditions.On the other hand the 4-methoxybenzyl thioether protecting group is totally unaffected by the conditions for oxidative deblocking of the S-trityl functions by either iodine or rhodanolysis.This opens up new opportunities for the directed synthesis of cystinyl peptides with more than one intra- or interchain disulfide bridge.Application of the new method to the synthesis of a cystine peptide with one intrachain S-S-bridge and a double-chain biscystinyl peptide is reported.
- Platen, Martin,Steckhan, Eberhard
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p. 1563 - 1576
(2007/10/02)
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