- Searching for improved mimetic peptides inhibitors preventing conformational transition of amyloid-β42 monomer
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A series of novel mimetic peptides were designed, synthesised and biologically evaluated as inhibitors of Aβ42 aggregation. One of the synthesised peptidic compounds, termed compound 7 modulated Aβ42 aggregation as demonstrated by thioflavin T fluorescence, acting also as an inhibitor of the cytotoxicity exerted by Aβ42 aggregates. The early stage interaction between compound 7 and the Aβ42 monomer was investigated by replica exchange molecular dynamics (REMD) simulations and docking studies. Our theoretical results revealed that compound 7 can elongate the helical conformation state of an early stage Aβ42 monomer and it helps preventing the formation of β-sheet structures by interacting with key residues in the central hydrophobic cluster (CHC). This strategy where early “on-pathway” events are monitored by small molecules will help the development of new therapeutic strategies for Alzheimer's disease.
- Gera, János,Sz?gi, Titanilla,Bozsó, Zsolt,Fül?p, Livia,Barrera, Exequiel E.,Rodriguez, Ana M.,Méndez, Luciana,Delpiccolo, Carina M.L.,Mata, Ernesto G.,Cioffi, Federica,Broersen, Kerensa,Paragi, Gabor,Enriz, Ricardo D.
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p. 211 - 221
(2018/08/24)
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- Synthesis of selenoxo peptides and oligoselenoxo peptides employing LiAlHSeH
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Synthesis of selenoxo peptides by the treatment of Nα- protected peptide esters with a combination of PCl5 and LiAlHSeH is delineated. The method is simple, high-yielding, and free from racemization. Thus obtained selenoxo peptides are used as units for N-terminal chain extension through Nα-deprotection/coupling to yield peptide-selenoxo peptide hybrids. Multiple selenation is demonstrated by conversion of two peptide bonds of tripeptides into selenoxo peptide bonds. Amino acid derived arylamides are also converted into aryl selenoamides. C6H 5-CSeNH-Val-OMe 8f is obtained as single crystal, and its structure was determined through X-ray diffraction study.
- Vishwanatha,Narendra,Chattopadhyay, Basab,Mukherjee, Monika,Sureshbabu, Vommina V.
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experimental part
p. 2689 - 2702
(2012/06/01)
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- Characterization of Nα-Fmoc-protected dipeptide isomers by electrospray ionization tandem mass spectrometry (ESI-MSn): Effect of protecting group on fragmentation of dipeptides
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A series of positional isomeric pairs of Fmoc-protected dipeptides, Fmoc-Gly-Xxx-OY/Fmoc-Xxx-Gly-OY (Xxx = Ala, Val, Leu, Phe) and Fmoc-Ala-Xxx-OY/Fmoc-Xxx-Ala-OY (Xxx = Leu, Phe) (Fmoc = [(9-fluorenylmethyl) oxy]carbonyl) and Y = CH3/H), have been characterized and differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-IT-MSn). In contrast to the behavior of reported unprotected dipeptide isomers which mainly produce y 1+ and/or a1+ ions, the protonated Fmoc-Xxx-Gly-OY, Fmoc-Ala-Xxx-OY and Fmoc-Xxx-Ala-OY yield significant b 1+ ions. These ions are formed, presumably with stable protonated aziridinone structures. However, the peptides with Gly- at the N-terminus do not form b1+ ions. The [M + H]+ ions of all the peptides undergo a McLafferty-type rearrangement followed by loss of CO2 to form [M + H-Fmoc + H]+. The MS3 collision-induced dissociation (CID) of these ions helps distinguish the pairs of isomeric dipeptides studied in this work. Further, negative ion MS 3 CID has also been found to be useful for differentiating these isomeric peptide acids. The MS3 of [M-H-Fmoc + H]- of isomeric peptide acids produce c1-, z1 - and y1- ions. Thus the present study of Fmoc-protected peptides provides additional information on mass spectral characterization of the dipeptides and distinguishes the positional isomers. Copyright
- Ramesh,Raju,Srinivas,Sureshbabu,Vishwanatha,Hemantha
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p. 1949 - 1958
(2012/05/20)
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- Microwave irradiated high-speed solution synthesis of peptide acids employing Fmoc-amino acid pentafluorophenyl esters as coupling agents
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A high-speed solution phase synthesis of peptide acids employing commercially available Fmoc-amino acid pentafluorophenyl esters as coupling agents has been demonstrated. The coupling has been found to be fast and completed in 30-45 sec. A simple work-up of the reaction mixture has resulted N-protected peptide acids in good yield. Utilizing the present method, the coupling of difficult sequences containing highly hindered α, α-dialkyl amino acids has also been demonstrated. Further, the synthesis of diastereomeric dipeptides, Fmoc-Phg-Phe-OMe and Fmoc-D-Phg-Phe-OMe revealed that the coupling is free from racemization.
- Suresh Babu, Vommina V.,Ramana Rao
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p. 2328 - 2332
(2007/10/03)
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- Potential formation of intramolecular inclusion complexes in peptidocyclodextrins as evidenced by NMR spectroscopy
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Investigations of the structure of β- and γ-cyclodextrin derivatives in solution obtained by grafting amino acids or peptides are presented.These compounds are models for vectorization-dedicated molecular carriers.It is shown that for some amino acids, strong intramolecular self-inclusion complexes are formed in aqueous solution.This process strongly depends upon the nature and position of the pertinent amino acid in the peptide sequence.Two dimensional NMR experiments are used in conjunction with competition with external guests to evidence and estimate the strength of these auto-inclusion complexes.
- Djedaini-Pilard, Florence,Azaroual-Bellanger, Nathalie,Gosnat, Muriel,Vernet, Delphine,Perly, Bruno
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p. 723 - 730
(2007/10/02)
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