- AZETIDIN-3-YLMETHANOL DERIVATIVES AS CCR6 RECEPTOR MODULATORS
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The present invention relates to compounds of Formula (I), their synthesis and use as CCR6 receptor modulators for the treatment or prevention of various diseases, conditions or disorders.
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Page/Page column 170; 171
(2021/11/06)
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- Oxidative damage of proline residues by nitrate radicals (NO3): A kinetic and product study
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Tertiary amides, such as in N-acylated proline or N-methyl glycine residues, react rapidly with nitrate radicals (NO3) with absolute rate coefficients in the range of 4-7 × 108 M-1 s-1 in acetonitrile. The major pathway proceeds through oxidative electron transfer (ET) at nitrogen, whereas hydrogen abstraction is only a minor contributor under these conditions. However, steric hindrance at the amide, for example by alkyl side chains at the α-carbon, lowers the rate coefficient by up to 75%, indicating that NO3-induced oxidation of amide bonds proceeds through initial formation of a charge transfer complex. Furthermore, the rate of oxidative damage of proline and N-methyl glycine is significantly influenced by its position in a peptide. Thus, neighbouring peptide bonds, particularly in the N-direction, reduce the electron density at the tertiary amide, which slows down the rate of ET by up to one order of magnitude. The results from these model studies suggest that the susceptibility of proline residues in peptides to radical-induced oxidative damage should be considerably reduced, compared with the single amino acid.
- Nathanael, Joses G.,Nuske, Madison R.,Richter, Annika,White, Jonathan M.,Wille, Uta
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supporting information
p. 6949 - 6957
(2020/10/02)
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- Bio- And Medicinally Compatible α-Amino-Acid Modification via Merging Photoredox and N-Heterocyclic Carbene Catalysis
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An N-heterocyclic carbene and photoredox cocatalyzed α-amino-acid decarboxylative carbonylation reaction is presented. This method displays good scope generality, providing a direct pathway to access various downstream α-amino ketones under bio- and medicinally compatible conditions. Moreover, this strategy is appealing to chemical biology because it has great potential for the chemical modification of peptides or the late-stage synthesis of keto-peptides.
- Chen, Lei,Du, Ding,Feng, Jie,Gao, Jian,Lu, Tao,Ma, Rui,Shi, Zhihao,Zhang, Kuili
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supporting information
(2020/09/02)
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- Oxidative Damage in Aliphatic Amino Acids and Di- and Tripeptides by the Environmental Free Radical Oxidant NO3?: the Role of the Amide Bond Revealed by Kinetic and Computational Studies
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Kinetic and computational data reveal a complex behavior of the important environmental free radical oxidant NO3? in its reactions with aliphatic amino acids and di- and tripeptides, suggesting that attack at the amide N-H bond in the peptide backbone is a highly viable pathway, which proceeds through a proton-coupled electron transfer (PCET) mechanism with a rate coefficient of about 1 × 106 M-1 s-1 in acetonitrile. Similar rate coefficients were determined for hydrogen abstraction from the α-carbon and from tertiary C-H bonds in the side chain. The obtained rate coefficients for the reaction of NO3? with aliphatic di- and tripeptides suggest that attack occurs at all of these sites in each individual amino acid residue, which makes aliphatic peptide sequences highly vulnerable to NO3?-induced oxidative damage. No evidence for amide neighboring group effects, which have previously been found to facilitate radical-induced side-chain damage in phenylalanine, was found for the reaction of NO3? with side chains in aliphatic peptides.
- Nathanael, Joses G.,Wille, Uta
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p. 3405 - 3418
(2019/03/11)
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- Conformational manifold of α-aminoisobutyric acid (Aib) containing alanine-based tripeptides in aqueous solution explored by vibrational spectroscopy, electronic circular dichroism spectroscopy, and molecular dynamics simulations
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Replacement of the α-proton of an alanine residue to generate α-aminoisobutyric acid (Aib) in alanine-based oligopeptides favors the formation of a 310 helix when the length of the oligopeptide is about four to six residues. This research was aimed at experimentally identifying the structural impact of an individual Aib residue in an alanine context of short peptides in water and Aib's influence on the conformation of nearest-neighbor residues. The amide I band profile of the IR, isotropic and anisotropic Raman, and vibrational circular dichroism (VCD) spectra of Ac-Ala-Ala-Aib-OMe, Ac-Ala-Aib-Ala-OMe, and Ac-Aib-Ala-Ala-OMe were measured and analyzed in terms of different structural models by utilizing an algorithm that exploits the excitonic coupling between amide I′ modes. The conformational search was guided by the respective 1H NMR and electronic circular dichroism spectra of the respective peptides, which were also recorded. From these analyses, all peptides adopted multiple conformations. Aib predominantly sampled the right-handed and left-handed 310-helix region and to a minor extent the bridge region between the polyproline (PPII) and the helical regions of the Ramachandran plot. Generally, alanine showed the anticipated PPII propensity, but its conformational equilibrium was shifted towards helical conformations in Ac-Aib-Ala-Ala-OMe, indicating that Aib can induce helical conformations of neighboring residues positioned towards the C-terminal direction of the peptide. An energy landscape exploration by molecular dynamics simulations corroborated the results of the spectroscopic studies. They also revealed the dynamics and pathways of potential conformational transitions of the corresponding Aib residues.
- Schweitzer-Stenner, Reinhard,Gonzales, Widalys,Bourne, Gregory T.,Feng, Jianwen A.,Marshall, Garland R.
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p. 13095 - 13109
(2008/03/30)
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- Fungal metabolites. XVII. Synthesis and NMR study of ion channel-forming peptides, trichosporin B-VIa and its derivative
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A membrane-modifying peptide antibiotic, trichosporin B-VIa, having catecholamine secretion-inducing activity on bovine adrenal chromaffin cells has been synthesized. Aib14-Trichosporin B-Vla, in which Pro14 was replaced by Aib, has
- Nagaoka,Iida,Fujita
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p. 1258 - 1263
(2007/10/02)
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- Fungal metabolites. IX. Synthesis of a membrane-modifying peptide, hypelcin A-III, from Hypocrea peltata
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A membrane-modifying peptide antibiotic having uncoupling activity on rat liver mitochondria, hypelcin A-III, has been synthesized by assembling five peptide fragments via the N,N'-dicyclohexylcarbodiimide method. The synthesized hypelcin A-III was identi
- Matsuura,Yesilada,Iida,Nagaoka,Takaishi,Fujita
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p. 1955 - 1959
(2007/10/02)
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- SYNTHESE VON 2-METHYLALANIN-PEPTIDEN, DIE pH-ABHAENGIGKEIT IHRER 13C-NMR-SPECTREN UND EINE NEUE METHODE ZUR AUSWERTUNG UEBER CS-DIAGRAMME
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The uncommon amino-acid 2-methylalanine (α-aminoisobutiryc acid, Aib) was investigated by 13C-NMR.The chemical shifts of amino- or carboxy-protected derivates of Aib and of protected oligopeptides are discussed with respect to neighbouring groups and amino acids.The pH-dependence of the 13C-NMR spectra of Aib, Aib-Ala, Ala-Aib, Aib-Ala-Aib and Aib-Ala-Aib-Ala-Aib was studied.Using these examples, a new and advantageous method is demonstrated for the first time for the evaluation of NMR titration curves, which uses so-called chemical shift diagrams (CS diagrams).
- Leibfritz, Dieter,Haupt, Erhard,Dubischar, Norbert,Lachmann, Heinrich,Oekonomopulos, Raymond,Jung, Guenther
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p. 2165 - 2182
(2007/10/02)
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