53100-44-0Relevant articles and documents
Synthetic approaches to peptides containing the l-Gln-l-Val-D(S)-Dmt motif
Suaifan, Ghadeer A.R.Y.,Arafat, Tawfiq,Threadgill, Michael D.
, p. 3474 - 3488 (2008/02/05)
The pseudoprolines S-Dmo (5,5-dimethyl-4-oxaproline) and R-Dmt (5,5-dimethyl-4-thiaproline) have been used to study the effects of forcing a fully cis conformation in peptides. Synthesis of peptides containing these (which have the same configuration as l-Pro) is straightforward. However, synthesis of peptides containing S-Dmt is difficult, owing to the rapid cyclisation of l-Aaa-S-Dmt amides and esters to form the corresponding diketopiperazines (DKP); thus the intermediacy of l-Aaa-S-Dmt amides and esters must be avoided in the synthetic sequence. Peptides containing the l-Gln-l-Val-D(S)-Dmt motif are particularly difficult, owing to the insolubility of coupling partners containing Gln. Introduction of Gln as N-Boc-pyroglutamate overcame the latter difficulty and the dipeptide active ester BocPygValOC6F5 coupled in good yield with S-DmtOH. BocPygVal-S- DmtNH(CH2)2C6H4NO2 was converted quantitatively to BocGlnVal-S-DmtNH(CH2)2C6H4NO2 with ammonia, demonstrating the utility of this approach. Two peptide derivatives (CbzSerLysLeuGlnVal-S-DmtNH(CH2)2C6H4NO2 and CbzSerSerLysLeuGlnVal-S- DmtNH(CH2)2C6H4NO2) were assembled, using these new methods of coupling a dipeptide acid active ester with S-DmtOH and introduction of Gln as Pyg, followed by conventional peptide couplings. The presence of the Val caused these peptides to be cleaved very slowly by prostate-specific antigen (PSA) at Leu ↓ Gln, rather than the expected Gln ↓ Val.
Pseudopeptide foldamers: the homo-oligomers of pyroglutamic acid.
Bernardi, Fernando,Garavelli, Marco,Scatizzi, Marco,Tomasini, Claudia,Trigari, Valerio,Crisma, Marco,Formaggio, Fernando,Peggion, Cristina,Toniolo, Claudio
, p. 2516 - 2525 (2007/10/03)
As a part of a program evaluating substituted gamma-lactams as conformationally constrained building blocks of pseudopeptide foldamers, we synthesized the homo-oligomers of L-pyroglutamic acid up to the tetramer level by solution methods. The preferred conformation of this pseudopeptide series in structure-supporting solvents was assessed by FT-IR absorption, 1H NMR and CD techniques. In addition, the crystal structure of the N alpha-protected dimer was established by X-ray diffraction. A high-level DFT computational modeling was performed based on the crystallographic parameters. In this analysis, we demonstrated that an alpha C-H...O=C intramolecular hydrogen bond is responsible for the stabilization of the s-trans L-pGlu-L-pGlu conformation by 1.4 kcal mol-1. This effect can be easily detected by 1H NMR spectroscopy, owing to the anomalous chemical shifts of the alpha CH protons present in all of the oligomers. In summary, we have developed a new polyimide-based, foldameric structure that, if appropriately functionalized, has promise as a rigid scaffold for novel functions and applications.
Stereospecific synthesis of (2S,4R)-[5,5,5-2H3]leucine
August, Ryan A.,Khan, Jeffrey A.,Moody, Claire M.,Young, Douglas W.
, p. 507 - 514 (2007/10/03)
The first stereospecific chemical synthesis of a sample of the amino acid (2S)-leucine labelled in one of the diastereotopic methyl groups has been achieved using (2S)-pyroglutamic acid as a chiral template. This has been used to develop a method for assigning resonances to the diastereotopic methyl groups of the leucine residues in the 1H NMR spectra of proteins.
A Novel Synthesis of L-Pyroglutamic Acid Derivatives from L-Proline: Utility of N-Protecting Groups for Ruthenium Tetroxide Oxidation of Cyclic α-Amino Acids
Yoshifuji,Shigeyuki,Tanaka, Ken-ichi,Kawai, Tomoyuki,Nitta, Yoshihiro
, p. 3873 - 3878 (2007/10/02)
The utility of four urethane type N-protecting groups, benzyloxycarbonyl (Z), p-nitrobenzyloxycarbonyl , trichloroethoxycarbonyl (Troc) and tert-butoxycarbonyl (Boc) groups, was tested in the ruthenium tetroxide (RuO4) oxidation of N-protected L-proline esters.Three groups, but not the Z group, which was decomposed by RuO4, were found to be stable during the oxidation and afforded high yields of the corresponding L-pyroglutamic acid esters.Removal of the protecting groups from the oxidation products was carried out successfully in the usual manner to give N-unsubstituted (NH-type) L-pyroglutamic acid derivatives without racemization.The first transformation of L-proline into L-pyroglutamic acid and its derivatives has been accomplished.Keywords - oxidation; ruthenium tetroxide oxidation; lactam synthesis; L-pyroglutamic acid synthesis; carboxamide N-protection; ruthenium tetroxide; L-proline; L-pyroglutamic acid; twophase method.
