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Mono thiomalonates (MTMs) are introduced as thioester enolate equivalents. Asymmetric organocatalyzed conjugate addition reactions to nitroolefins proceed under mild conditions to afford synthetically useful γ-nitrothioesters with excellent yields and enantioselectivities. 相似文献
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A straightforward synthesis of orthogonally protected nucleoproline (Nup) amino acids and their coupling to oligomers are described. A key step is the attachment of alkynylated nucleobases to Fmoc‐protected 4‐azidoproline (Fmoc‐Azp‐OH) by a Cu‐catalyzed 1,3‐dipolar cycloaddition (‘click reaction’). The developed protocol allows preparation of the nucleoprolines in scales of >30 g. Solid‐phase peptide synthesis proved to be straightforward with these Nup amino acids. The resulting oligonucleoproline peptides adopt defined helices, are very well H2O soluble, and show comparable cell‐penetrating properties as recently reported α‐nucleoalanine peptides. 相似文献
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Marc‐Andr Kasper Maria Glanz Andreas Stengl Martin Penkert Simon Klenk Tom Sauer Dominik Schumacher Jonas Helma Eberhard Krause M. Cristina Cardoso Heinrich Leonhardt Christian P. R. Hackenberger 《Angewandte Chemie (International ed. in English)》2019,58(34):11625-11630
We describe a new technique in protein synthesis that extends the existing repertoire of methods for protein modification: A chemoselective reaction that induces reactivity for a subsequent bioconjugation. An azide‐modified building block reacts first with an ethynylphosphonite through a Staudinger‐phosphonite reaction (SPhR) to give an ethynylphosphonamidate. The resulting electron‐deficient triple bond subsequently undergoes a cysteine‐selective reaction with proteins or antibodies. We demonstrate that ethynylphosphonamidates display excellent cysteine‐selective reactivity combined with superior stability of the thiol adducts, when compared to classical maleimide linkages. This turns our technique into a versatile and powerful tool for the facile construction of stable functional protein conjugates. 相似文献
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The effect of β3‐amino acids on the conformation and catalytic performance of the peptidic catalyst H‐d Pro‐Pro‐Glu‐NH2 was investigated. Analogues of the peptidic catalyst bearing instead of the α‐amino acids the respective β3‐amino acids were prepared and their reactivity and stereoselectivity was investigated in conjugate addition reactions of aldehydes to nitroolefins. Additional computational studies provided insights into the preferred conformations of the peptidic catalysts. The results show that conformational flexibility at the N‐terminus has a severe effect on the stereoselectivity but is tolerated at the C‐terminus. 相似文献
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Michal S. Shoshan Thomas Vonderach Bodo Hattendorf Helma Wennemers 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4955-4959
Peptide‐stabilized platinum nanoparticles (PtNPs) were developed that have significantly greater toxicity against hepatic cancer cells (HepG2) than against other cancer cells and non‐cancerous liver cells. The peptide H‐Lys‐Pro‐Gly‐d Lys‐NH2 was identified by a combinatorial screening and further optimized to enable the formation of water‐soluble, monodisperse PtNPs with average diameters of 2.5 nm that are stable for years. In comparison to cisplatin, the peptide‐coated PtNPs are not only more toxic against hepatic cancer cells but have a significantly higher tumor cell selectivity. Cell viability and uptake studies revealed that high cellular uptake and an oxidative environment are key for the selective cytotoxicity of the peptide‐coated PtNPs. 相似文献
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Stereoselective Organocatalyzed Synthesis of α‐Fluorinated β‐Amino Thioesters and Their Application in Peptide Synthesis 下载免费PDF全文
Dr. Jakub Saadi Dr. Marc‐Olivier Ebert Prof. Dr. Helma Wennemers 《Angewandte Chemie (International ed. in English)》2016,55(42):13127-13131
α‐Fluorinated β‐amino thioesters were obtained in high yields and stereoselectivities by organocatalyzed addition reactions of α‐fluorinated monothiomalonates (F‐MTMs) to N‐Cbz‐ and N‐Boc‐protected imines. The transformation requires catalyst loadings of only 1 mol % and proceeds under mild reaction conditions. The obtained addition products were readily used for coupling‐reagent‐free peptide synthesis in solution and on solid phase. The α‐fluoro‐β‐(carb)amido moiety showed distinct conformational preferences, as determined by crystal structure and NMR spectroscopic analysis. 相似文献
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Kirsten Belser Dr. Tünde Vig Slenters Dipl.‐Chem. Conelious Pfumbidzai Grégory Upert Dr. Laurent Mirolo Katharina M. Fromm Prof. Dr. Helma Wennemers Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(20):3661-3664
Split‐and‐mix libraries are an excellent tool for the identification of peptides that induce the formation of Ag nanoparticles in the presence of either light or sodium ascorbate to reduce Ag+ ions. Structurally diverse peptides were detected in colorimetric on‐bead screenings that generate Ag nanoparticles of different sizes, as confirmed by SEM and X‐ray powder diffraction studies.
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Kalb SR Baudys J Rees JC Smith TJ Smith LA Helma CH Hill K Kull S Kirchner S Dorner MB Dorner BG Pirkle JL Barr JR 《Analytical and bioanalytical chemistry》2012,403(1):215-226
Botulinum neurotoxins (BoNTs) cause the disease botulism, which can be lethal if untreated. There are seven known serotypes of BoNT, A-G, defined by their response to antisera. Many serotypes are distinguished into differing subtypes based on amino acid sequence, and many subtypes are further differentiated into toxin variants. Previous work in our laboratory described the use of a proteomics approach to distinguish subtype BoNT/A1 from BoNT/A2 where BoNT identities were confirmed after searching data against a database containing protein sequences of all known BoNT/A subtypes. We now describe here a similar approach to differentiate subtypes BoNT/B1, /B2, /B3, /B4, and /B5. Additionally, to identify new subtypes or hitherto unpublished amino acid substitutions, we created an amino acid substitution database covering every possible amino acid change. We used this database to differentiate multiple toxin variants within subtypes of BoNT/B1 and B2. More importantly, with our amino acid substitution database, we were able to identify a novel BoNT/B subtype, designated here as BoNT/B7. These techniques allow for subtype and strain level identification of both known and unknown BoNT/B rapidly with no DNA required. 相似文献
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