- Investigation of pH-dependent collagen triple-helix formation
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(Figure Presented) Helices on demand: Collagen peptides were engineered to form triple helices under environmental control. The replacement of the hydroxyproline (Hyp) residues in a collagen peptide with carboxylate-modified Hyp residues gave a petide tha
- Lee, Song-Gil,Lee, Jee Yeon,Chmielewski, Jean
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Read Online
- Design and synthesis of fluorinated peptides for analysis of fluorous effects on the interconversion of polyproline helices
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The unique interaction between fluorine atoms has been exploited to alter protein structures and to develop synthetic and analytical applications. To expand such fluorous interaction for novel applications, polyproline peptides represent an excellent molecular nanoscaffold for controlling the presentation of perfluoroalkyl groups on their unique secondary structure. We develop approaches to synthesis fluorinated peptides to systematically investigate how the number, location and types of the fluorous groups on polyproline affect the conformation by monitoring the transition between the two major polyproline structures PPI and PPII. This work provides valuable information on how fluorous interaction affects the peptide structure and also benefits the design of functional fluorous molecules.
- Li, Meng-Che,Liu, Ying-Jie,Hsu, Kuang-Cheng,Lin, Tse-Hsueh,Lin, Chih-Wei,Horng, Jia-Cherng,Wang, Sheng-Kai
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- Structural development of cell-penetrating peptides containing cationic proline derivatives
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We designed and synthesized a series of cell-penetrating peptides containing cationic proline derivatives (ProGu) that exhibited responsive changes in their secondary structures to the cellular environment. Effects of the peptide length and steric arrangement of the side chain in cationic proline derivatives [Pro4SGu and Pro4RGu] on their secondary structures and cell membrane permeability were investigated. Moreover, peptides 3 and 8 exhibited efficient intracellular delivery of plasmid DNA.
- Kobayashi, Hiroyuki,Misawa, Takashi,Oba, Makoto,Hirata, Naoya,Kanda, Yasunari,Tanaka, Masakazu,Matsuno, Kenji,Demizu, Yosuke
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p. 575 - 580
(2018/05/07)
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- CYCLIC PEPTIDES AS C5 A RECEPTOR ANTAGONISTS
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The invention relates to cyclic peptide derivatives, to their use in medicine, to compositions containing them, to processes for their preparation and to intermediates used in such processes. More particularly the invention relates to cyclic peptide C5a receptor antagonists of formula (Ia)or formula (Ib), or pharmaceutically acceptable salts thereof,wherein R1a, R1b, R2, R3 and R4 areas defined in the description. C5a receptor antagonists are potentially useful in the treatment of a wide range of 1 disorders,including inflammatory disorders and immune disorders.
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Page/Page column 85
(2018/02/28)
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- Scaling the Amphiphilic Character and Antimicrobial Activity of Gramicidin S by Dihydroxylation or Ketal Formation
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The acid lability of aliphatic ketals, which often serve as protection groups for 1,2-diols, is influenced by their local structural environment. The acetonide of the protected amino acid cis-dihydroxyproline (Dyp) is a typical protecting group cleavable by traces of TFA. The tricyclic acetonide of the dipeptide d-Hot-Tap is resistant to TFA and thus can serve as a bioorthogonal modification of bioactive peptides. With the aim of improving antimicrobial activity and hemolytic properties, we use these reactivity differences to scale the membrane affinity of the decapeptide Gramicidin S cyclo(d-Phe-Pro-Val-Orn-Leu-)2 (GS). The cis-dihydroxylated amino acids are used to increase the polarity of GS or obversely decrease the polarity by stereoselective ketal formation with an aliphatic ketone. While Dyp (GS mimetic 15) has only minimal influence on the biological properties of GS, d-Hot-Tap at the position of d-Phe1-Pro2 eradicates the biological activity (GS mimetic 16). The acid-stable ketals 17-19 are bioorthogonal modifications which reconstitute the biological activity of GS. We describe an improved synthesis of orthogonally protected Fmoc-Dyp-acetonide (9) and of several Fmoc-d-Hot-Tap-ketals for solid-phase peptide synthesis.
- Priem, Christoph,Wuttke, André,Berditsch, Marina,Ulrich, Anne S.,Geyer, Armin
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p. 12366 - 12376
(2017/12/08)
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- Cu(i)-Functionalized SBA-16: An efficient catalyst for the synthesis of α-ketoamides under moderate conditions
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An efficient catalyst based on the cage-like mesoporous material SBA-16 as the support and Cu(i) as active sites has been successfully prepared. The catalyst demonstrated high catalytic activity (up to 88%) in the direct oxidative synthesis of α-ketoamides between acetophenone and piperidine, employing O2 from open air as the oxidant without other additives. A heterogeneous catalyst was applied in this reaction for the first time, and the catalyst could be easily separated from the reaction system by filtration and reused several times without a significant loss of activity.
- Zhang, Xueyao,Yang, Honglei,Huo, Yong,Li, Jing,Ma, Jianxin,Ma, Jiantai
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p. 8972 - 8983
(2016/06/09)
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- Novel Inhibitors of the Amino Acid Transporters ASCT1 and ASCT2
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The invention features compounds and methods relating to novel hydroxy-proline analog inhibitors of the ASCT1 and ASCT2 neutral amino acid transporters. These analogs are potent and selective inhibitors of ASCT2 and ASCT1-mediated amino acid transport as evidenced by significantly reduced glutamine or alanine transport-associated currents or radiolabeled substrate (amino acid) uptake in Xenopus oocytes expressing ASCT2 or ASCT1. Selectivity has been established in the same manner whereby reduced substrate associated current or substrate uptake is unobserved in Xenopus oocytes expressing ATA2, SN1, or EAAT(s) (excitatory amino acid transporter). The compounds and methods of the invention can be used in research or clinical applications (e.g., for the treatment of cancer, microbial infection, or ischemia-related central nervous system injury).
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Paragraph 0097; 0098
(2013/03/28)
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- Core-shell silica magnetic microspheres supported proline as a recyclable organocatalyst for the asymmetric aldol reaction
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l-4-Hydroxyproline has been successfully grafted onto the core-shell structural silica magnetic microspheres and characterized by elemental analysis, thermo gravimetric analysis (TGA), vibrating sample magnetometry (VSM), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared (FT-IR). The chiral immobilized catalyst demonstrated high catalytic activity (up to 92%), diastereoselectivity (up to 85:15) and enantioselectivity (up to 80%) in the asymmetric aldol reaction between aldehyde acceptors and ketone donors. On the other hand, the synthesized catalyst could be rapidly separated from the reaction mixture through an external magnetic field and reused up to five runs without any obvious loss of activity, indicating its easy-separated property and excellent recyclability.
- Yang, Honglei,Li, Shuwen,Wang, Xiaoyu,Zhang, Fengwei,Zhong, Xing,Dong, Zhengping,Ma, Jiantai
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p. 404 - 410,7
(2020/07/30)
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- L-proline-catalyzed asymmetric michael addition of 2-oxindoles to enones: A convenient access to oxindoles with a quaternary stereocenter
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A new organocatalytic approach for 1,4-conjugate addition of 2-oxindoles to α,β-unsaturated ketones using the combination of readily available and nonexpensive l-proline and achiral trans-2,5-dimethylpiperazine as catalytic system is provided. The reaction results in oxindole derivatives with vicinal quaternary and tertiary carbon centers in up to 99% yield and 91% ee. Georg Thieme Verlag Stuttgart.
- Freund, Matthias H.,Tsogoeva, Svetlana B.
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supporting information; scheme or table
p. 503 - 507
(2011/04/18)
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- Imidazolium ion-tagged proline organocatalyst for α-aminoxylation of aldehydes and ketones in ionic liquids
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A novel imidazolium ion-tagged L-proline catalyst has been developed. The asymmetric α-aminoxylation of aldehydes and ketones with excellent enantioselectivities, up to 99% ee, and high yields in ionic liquids has been achieved. The system can be easily recycled and reused for at least six times without significant loss of yields and enantioselectivity.
- Ding, Xiong,Tang, Wenming,Zhu, Chengjian,Cheng, Yixiang
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supporting information; scheme or table
p. 108 - 112
(2010/06/21)
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- Synthesis of novel haptens and conjugates for antibody production against kainoid family
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Amnesic shellfish poisoning (ASP) is caused by consumption of contaminated seafood that has accumulated kainic acid or kainoid analogues such as domoic acid. Among the different ASP bioassays, immunoassays are an attractive alternative to the in vivo mouse bioassay. Herein, we report the synthesis and bioconjugation of two new haptens for the generation of a specific antibody against members of the kainoid family. Georg Thieme Verlag Stuttgart.
- Baco, Etienne,Vellutini, Luc,Pillot, Jean-Paul,Felpin, Fran?ois-Xavier,Schmitter, Jean-Marie,Bennetau, Bernard,Degueil, Marie
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scheme or table
p. 1943 - 1946
(2010/10/02)
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- Organocatalytic tunable amino acid polymers prepared by controlled radical polymerization
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Two families of organocatalytically active polystyrene-based copolymers with tunable incorporations of 4-hydroxyproline have been synthesized using two different controlled radical polymerization technologies: nitroxide-mediated polymerization (NMP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. Both of these methodologies allow ready access to a number of polymeric species with controllable molecular weights, narrow molecular weight distributions (ca. 1.2), and reliable functionality incorporations (between 3 and 26%). The organocatalytic activity and selectivity of the NMP-derived family of copolymers with variable incorporations of l-proline have been investigated using the aldol reaction, which provided high conversion to products (>95%) with very good diastereo- and enantioselectivities. We propose that these materials have potential as highly efficient recoverable organocatalyst supports whose solubility and loading can be readily tailored to the desired application.
- Evans, Amanda C.,Lu, Annhelen,Ondeck, Courtney,Longbottom, Deborah A.,O'Reilly, Rachel K.
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scheme or table
p. 6374 - 6380
(2011/11/01)
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- New simple hydrophobic proline derivatives as highly active and stereoselective catalysts for the direct asymmetric Aldol reaction in aqueous medium
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New 4-substituted acyloxyproline derivatives with different hydrophobic properties of the acyl group were easily synthesized and used as catalysts in the direct asymmetric aldol reaction between cyclic ketones (cyclohexanone and cyclopentanone) and severa
- Giacalone, Francesco,Gruttadauria, Michelangelo,Lo Meo, Paolo,Riela, Serena,Noto, Renato
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scheme or table
p. 2747 - 2760
(2009/10/02)
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- An enantioselective nucleophilic addition of α,β-unsaturated trifluoromethylketones catalyzed by l-proline derivatives
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An unexpected enantioselective 1,2-aldol reaction of acetone with α,β-unsaturated trifluoromethylketone catalyzed by l-proline derivative was described. The absolute configuration of the resulting chiral product was assigned based on a single crystal X-ray diffraction analysis. Structure-reactivity study of this organocatalytic system was briefly discussed. A reaction mechanism was tentatively postulated.
- Zhang, Dehui,Yuan, Chengye
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p. 2480 - 2488
(2008/09/18)
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- Protected aminooxyprolines for expedited library synthesis: Application to Tsg101-directed proline-oxime containing peptides
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The stereoselective synthesis of aminooxy-containing proline analogues bearing Fmoc/Boc or Fmoc/Mtt protection that renders them suitable for incorporation into peptides using Fmoc protocols is reported. Acid-catalyzed unmasking at the completion of peptide synthesis yields free aminooxy-functionalities for oxime formation through reaction with libraries of aldehydes. This allows post solid-phase diversification strategies that may facilitate structure-activity relationship studies.
- Liu, Fa,Stephen, Andrew G.,Fisher, Robert J.,Burke Jr., Terrence R.
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p. 1096 - 1101
(2008/09/19)
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- Asymmetric aldol reaction catalyzed by a heterogenized proline on a mesoporous support. The role of the nature of solvents
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(Chemical Equation Presented) A heterogenized (S)-proline on mesoporous support MCM-41 catalyzes the asymmetric aldol reaction in a wide range of solvents. The progress of the reaction is dependent on the nature of the solvent. Reactions proceed more effi
- Doyagueez, Elisa G.,Calderon, Felix,Sanchez, Felix,Fernandez-Mayoralas, Alfonso
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p. 9353 - 9356
(2008/03/14)
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- Highly efficient asymmetric direct stoichiometric aldol reactions on/in water
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(Figure Presented) Hydrophobic pocket pleaser: A novel asymmetric catalytic system in water mediated by sulfated β-cyclodextrin (see picture) can bind the organocatalyst tert-butylphenoxyproline and associated hydrophobic reactants. Enantio- and diastereoselectivities up to >99% and close to quantitative yields could be achieved for stoichiometric direct aldol reactions of cyclohexanone and aryl aldehydes with this system.
- Huang, Junmin,Zhang, Xiaotong,Armstrong, Daniel W.
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p. 9073 - 9077
(2008/09/20)
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- Synthesis of conformationally constrained lysine analogues
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The synthesis of two conformationally constrained lysine analogues is reported. The synthesis of the novel analogue 1 based on the 3-aza-bicyclo[3.1.0]hexane system is accomplished from the known tricycle 3 in eight steps. The synthesis of the analogue 2 is accomplished in eight steps from 4-hydroxy proline. Both analogues are synthesized appropriately protected for Fmoc/Boc solid-phase peptide synthesis.
- Ganorkar, Rakesh,Natarajan, Amarnath,Mamai, Ahmed,Madalengoitia, Jose S.
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p. 5004 - 5007
(2007/10/03)
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- Asymmetric aldol reaction using immobilized proline on mesoporous support
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The aldol reaction of hydroxyacetone with different aldehydes using immobilized proline on a mesoporous support, assisted by heat and microwaves, has been explored. It was found that heterogenized L-proline on MCM-41 catalyzed aldol reactions in both hydr
- Calderon, Felix,Fernandez, Raquel,Sanchez, Felix,Fernandez-Mayoralas, Alfonso
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p. 1395 - 1403
(2007/10/03)
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- Catalysis with phosphine-containing amino acids in various "turn" motifs
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We have been actively involved in the development of parallel approaches for the discovery of phosphine ligands. Our approach has been based on the incorporation of phosphine-containing amino acids into peptide sequences that are designed to have stable secondary structures. We have examined helical and turn secondary structures and have reported that alkylation of cyclopentenyl acetate with dimethylmalonate can be catalyzed in high enantiomeric excess (ee) with a β-turn-based ligand. The importance of the peptide secondary structure was demonstrated through the synthesis of a series of peptide ligands where the nature of the turn-forming residues was probed. Additionally, other turn-forming units and a variety of different phosphine-containing amino acids have been examined for their ability to control the selectivity of the allylation reaction. This paper reports the results obtained through the examination of different turn motifs as well as different phosphine substitutions on the "best" turn sequence, Pps-Pro-D-Xxx-Pps.
- Agarkov, Anton,Greenfield, Scott J.,Ohishi, Takahiro,Collibee, Scott E.,Gilbertson, Scott R.
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p. 8077 - 8085
(2007/10/03)
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- Stereoselective synthesis of novel chimerical amino acids via a photochemical key step
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The synthesis of novel chimerical amino acid derivatives 6-8 bearing the 6-azatricyclo[3.3.1.033,7]nonane (methanotropane) skeleton is described. Starting with one chirality centre in L-4-oxoprolines 2 we succeeded in the fully stereoselective introduction of four new chirality centres. The key step of our synthetic route is a photochemical cyclization of phenyl ketones, whose stereoselectivity has been explained by the different stability of the triplet biradical conformers.
- Wessig, Pablo
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p. 1465 - 1467
(2007/10/03)
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- Synthesis of (2S, 3R, 4S), (2S, 3S, 4R)-epoxyprolines and aminohydroxyprolines
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25, 3R, 4S- and 25, 38, 4R-epoxy-L-prolines were synthesised from trans- 4-hydroxy-L-proline. Assignment of the stereochemical configurations of the epoxy prolines was achieved by n.O.e. studies and chemical correlation. The synthetic utility of the protected epoxides was investigated briefly by ring opening with NAN3, followed by deprotection to give aminohydroxy prolines.
- Robinson, J. Kenneth,Lee, Victor,Claridge, Timothy D. W.,Baldwin, Jack E.,Schofield, Christopher J.
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p. 981 - 996
(2007/10/03)
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- Synthesis of novel vitamin C phosphodiesters: Stability and antioxidant activity
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A novel series of hybrid L-ascorbic acid (vitamin C) phosphodiesters linked at the C-2 hydroxyl group with other biologically active substances, namely myo-inositol, arbutin, 4-hydroxy-L-proline, and glycolic acid were synthesized, and their thermal stability and reducing activity against free radicals were estimated in vitro. All of the phosphodiesters exhibited high thermal stabilities; however, their antioxidant activities in vitro were generally lower than that of vitamin C.
- Morisaki, Kazuo,Ozaki, Shoichiro
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p. 123 - 138
(2007/10/03)
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- Synthesis of De(hydroxymethyl)desulfo Analogues of Bulgecins A, B and C
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The syntheses of de(hydroxymethyl)desulfo analogues of Bulgecin A, B and C are described.Stereospecific β-glycosylation of aglycones was achieved using Schmidt's trichloroacetimidate metodology.
- Brown, Allan G.,Moss, Stephen F.,Southgate, Robert
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p. 451 - 454
(2007/10/02)
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- Electrochemical Oxidation of Proline Derivatives: Total Syntheses of Bulgecinine and Bulgecin C
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The influence of structure on the efficiency of the electrochemical C-5 oxidation of (2S,4S)-hydroxyproline carbamate esters is presented.Optimum methoxylation was observed with (2S,4S)-4-acetoxy-1,2-pyrrolidine-dicarboxylic acid 2-methyl 1-(2-(trimethylsilyl)ethyl) ester (19).The corresponding C-5 methoxy derivative 20 was converted into bulgecinine (4) via a stereospecific radical homologation to incorporate the C-5 hydroxymethyl substituent.Bulgecin C (1c) was prepared via a β-stereoselective glycosidation reaction using a 2-azido-2-deoxy-α-D-glucopyranosyl trichloroacetimidate derivative, regiospecific C-4' sulfation, and deprotection.
- Barrett, Anthony G. M.,Pilipauskas, Daniel
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p. 2787 - 2800
(2007/10/02)
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- Synthesis and Biological Activity of O-Glycosylated Morphiceptin Analogues
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The synthesis and biological activity of 4>morphiceptin and two glycosyl derivatives are reported.Glycopeptide amides were obtained using Fmoc solid phase chemistry and mild conditions for cleavage from a tris(alkoxy)benzylamide (PAL) resin
- Bardaji, Eduard,Torres, Joseph L.,Clapes, Pere,Albericio, Fernando,Barany, George,et al.
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p. 1755 - 1760
(2007/10/02)
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