69700-83-0Relevant academic research and scientific papers
Photocyclization of Tetra- and Pentapeptides Containing Adamantylphthalimide and Phenylalanines: Reaction Efficiency and Diastereoselectivity
Sohora, Margareta,Vazdar, Mario,Sovi?, Irena,Mlinari?-Majerski, Kata,Basari?, Nikola
, p. 14905 - 14922 (2019/01/04)
A series of tetrapeptides and pentapeptides was synthesized bearing a phthalimide chromophore at the N-terminus. The C-terminus of the peptides was strategically substituted with an amino acid, Phe, Phe(OMe), or Phe(OMe)2 characterized by different oxidation potentials. The photochemical reactivity of the peptides was investigated by preparative irradiation and isolation of photoproducts, as well as with laser flash photolysis. Upon photoexcitation, the peptides undergo photoinduced electron transfer (PET) and decarboxylation, followed by diastereoselective cyclization with the retention of configuration for tetrapeptides or inversion of configuration for pentapeptides. Molecular dynamics (MD) simulations and NOE experiments enabled assignment of the stereochemistry of the cyclic peptides. MD simulations of the linear peptides disclosed conformational reasons for the observed diastereoselectivity, being due to the peptide backbone spatial orientation imposed by the Phe amino acids. The photochemical efficiency for the decarboxylation and cyclization is not dependent on the peptide length, but it depends on the oxidation potential of the amino acid at the C-terminus. The results described herein are particularly important for the rational design of efficient photochemical reactions for the preparation of cyclic peptides with the desired selectivity.
Self-Assembly of Tetraphenylalanine Peptides
Mayans, Enric,Ballano, Gema,Casanovas, Jordi,Díaz, Angélica,Pérez-Madrigal, Maria M.,Estrany, Francesc,Puiggalí, Jordi,Cativiela, Carlos,Alemán, Carlos
, p. 16895 - 16905 (2015/11/16)
Three different tetraphenylalanine (FFFF) based peptides that differ at the N- and C-termini have been synthesized by using standard procedures to study their ability to form different nanoassemblies under a variety of conditions. The FFFF peptide assembles into nanotubes that show more structural imperfections at the surface than those formed by the diphenylalanine (FF) peptide under the same conditions. Periodic DFT calculations (M06L functional) were used to propose a model that consists of three FFFF molecules defining a ring through head-to-tail NH3+?-OOC interactions, which in turn stack to produce deformed channels with internal diameters between 12 and 16 ?. Depending on the experimental conditions used for the peptide incubation, N-fluorenylmethoxycarbonyl (Fmoc) protected FFFF self-assembles into a variety of polymorphs: ultra-thin nanoplates, fibrils, and star-like submicrometric aggregates. DFT calculations indicate that Fmoc-FFFF prefers a parallel rather than an antiparallel β-sheet assembly. Finally, coexisting multiple assemblies (up to three) were observed for Fmoc-FFFF-OBzl (OBzl = benzyl ester), which incorporates aromatic protecting groups at the two peptide terminals. This unusual and noticeable feature is attributed to the fact that the assemblies obtained by combining the Fmoc and OBzl groups contained in the peptide are isoenergetic. Variety show! Three different tetraphenylalanine-based peptides that differ at the N- and C-termini have been synthesized by using standard procedures to study their ability to form different nanoassemblies (e.g., nanotubes, see figure) under a variety of conditions.
Studies of Bitter Peptides from Casein Hydrolyzate. IV. Relationship between Bitterness and Hydrophobic Amino Acids Moiety in the C-Terminal of BPIa (Arg-Gly-Pro-Pro-Phe-Ile-Val)
Otagiri, Ken,Shigenaga, Toshiaki,Kanehisa, Hidenori,Okai, Hideo
, p. 90 - 96 (2007/10/02)
In the synthetic studies of bitter peptide BPIa (Arg-Gly-Pro-Pro-Phe-Ile-Val), we sythesized several BPIa analogs to elucidate the participation of the hydrophobic amino acids moiety in the C-terminal in the bitter taste exhibited by BPIa.The syntheses of
