- Solid-Phase Synthesis of Peptide Amides on a Polystyrene Support Using Fluorenylmethoxycarbonyl Protecting Groups
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We have investigated new routes for the synthesis of acid-sensitive amino acids using N-fluorenylmethoxycarbonyl amino acids and mild acid labile side chain protection in order to avoid HF cleavage as final step.The 4-(benzyloxy)benzylamine resin, applied successfully by Pietta and Brenna, proved to be unsuitable for the synthesis of peptide amides since we have found that trifluoroacetic acid treatment of peptide-resins yield the peptide still bearing a p-hydroxybenzyl group on the carboxamide nitrogen.We have successfully used the 2,4-dimethoxybenzhydrylamine support for the synthesis of peptide amides.Cholecystokinin octapeptide and GnRH were synthesized on the 2,4-dimethoxybenzhydrylamine resin and cleaved from the polymer with trifluoroacetic acid-thioanisole (4:1), and 95percent trifluroacetic acid containing phenol (2.5percent) and dimethyl sulfide (2.5percent), respectively.The final cleavage conditions had to be optimized in order to obtain good yields, suggesting that side chain protections of certain amino acids, possibly arginine and tryptophan, may have to be further refined.
- Penke, Botond,Rivier, Jean
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- Structure-Based Design of High-Affinity Fluorescent Probes for the Neuropeptide Y Y1Receptor
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The recent crystallization of the neuropeptide Y Y1 receptor (Y1R) in complex with the argininamide-type Y1R selective antagonist UR-MK299 (2) opened up a new approach toward structure-based design of nonpeptidic Y1R ligands. We designed novel fluorescent probes showing excellent Y1R selectivity and, in contrast to previously described fluorescent Y1R ligands, considerably higher (~100-fold) binding affinity. This was achieved through the attachment of different fluorescent dyes to the diphenylacetyl moiety in 2 via an amine-functionalized linker. The fluorescent ligands exhibited picomolar Y1R binding affinities (pKi values of 9.36-9.95) and proved to be Y1R antagonists, as validated in a Fura-2 calcium assay. The versatile applicability of the probes as tool compounds was demonstrated by flow cytometry- and fluorescence anisotropy-based Y1R binding studies (saturation and competition binding and association and dissociation kinetics) as well as by widefield and total internal reflection fluorescence (TIRF) microscopy of live tumor cells, revealing that fluorescence was mainly localized at the plasma membrane.
- Müller, Christoph,Gleixner, Jakob,Tahk, Maris-Johanna,Kopanchuk, Sergei,Laasfeld, T?nis,Weinhart, Michael,Schollmeyer, Dieter,Betschart, Martin U.,Lüdeke, Steffen,Koch, Pierre,Rinken, Ago,Keller, Max
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p. 4832 - 4853
(2022/03/27)
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- Synthesis of novel photochromic pyrans via palladium-mediated reactions
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Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based ?-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-substituted benzopyran 5a was investigated by time-resolved absorption spectroscopy in the picosecond time domain.
- Boettcher, Christoph,Zeyat, Gehad,Ahmed, Saleh A.,Irran, Elisabeth,Rueck-Braun, Karola,Cordes, Thorben,Elsner, Cord,Zinth, Wolfgang
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supporting information; experimental part
(2010/04/22)
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