Pseudo-Prolines as a Molecular Hinge: Reversible Induction of cis Amide Bonds into Peptide Backbones
摘要:
Serine, threonine-derived (4S)-oxazolidine-4-carboxylic acid, and cysteine-derived (4R)-thiazolidinecarboxylic acid, denoted pseudo-proline (Xaa[Psi(R1,R2)pro]), serve as structure disrupting, solubilizing building blocks in peptide synthesis. Variation of the 2-C substituents within the heterocyclic system results in different physicochemical and conformational properties. NMR studies of a series of pseudo-proline (Psi Pro)-containing peptides reveal a pronounced effect of the 2-C substituents upon the cis to trans ratio of the adjacent amide bond in solution. 2-C unsubstituted systems show a preference similar to that of the proline residue for the trans form, whereas 2,2-dimethylated derivatives adopt the cis amide conformation in high content. For 2-monosubstituted Psi Pro, the cis-trans distribution depends on the 2-C chirality. For the 2-(S)-diastereoisomer, both forms are similarly populated in solution, whereas the 2-(R)-epimer adopts preferentially the trans form. The results are supported by conformational energy calculations and suggest that, by tailoring the degree of substitution, pseudo-prolines may serve as a temporary proline mimetic or as a hinge in peptide backbones.
Traceless chemical ligations from O-acyl serine sites
作者:Mirna El Khatib、Mohamed Elagawany、Farukh Jabeen、Ekaterina Todadze、Oleg Bol'shakov、Alexander Oliferenko、Levan Khelashvili、Said A. El-Feky、Abdullah Asiri、Alan R. Katritzky
DOI:10.1039/c2ob07050b
日期:——
Chemicalligationvia O- to N-acyl transfer of O-acylated serine containing peptides affords serine containing native peptides via8- and 11-memberedcyclictransitionstates opening the door to a wide variety of potential applications to peptide elaboration. The feasibility of these traceless chemicalligations is feasible as supported by computation.
found to be an excellent coupling reagent having a water-soluble property and a high reactivity; it worked as satisfactory as usual activeesters in regard to the reactivity, product purity, and racemization. The marked advantage of the HODMSP·MeSO4− activeester method was the fact that bifunctional residues such as Arg, Lys, Cys, and Tyr could be selectively acylated when the pH of the reaction mixture
The coupling reactions of 3-phenylpropanoic acid and N-carboxybenzyl α-aminoacids with unprotected α-aminoacids containing hydrophilic side chains such as aliphatic alcohol, aromatic alcohol, thiol, carboxylic acid, and amide afforded the corresponding amides in 66–96% yield without racemization via the corresponding mixed carbonic carboxylic anhydrides under basic conditions through an ecological
A One-Pot Peptide Synthesis via<u>Se</u>-phenyl Carboselenoate in Mixed Aqueous/Organic Solvent System
作者:Sunil Kumar Ghosh、Usha Singh、Mohindra S. Chadha、Vasant R. Mamdapur
DOI:10.1246/bcsj.66.1566
日期:1993.5
A one pot synthesis of peptides with free C-terminal residues has been accomplished via the active Se-phenyl carboselenoate using diphenyl diselenide, tributylphosphine, and N-methylmorpholine N-oxide in an acetonitrile– water mixed solvent system. Free amino acids and peptides have been used as the amine component without pH adjustment.
MONITORED AMINOLYSIS OF 3-ACYL-l,3-THIAZ0LIDINE-2-THI0NE WITH AMINO ACID AND ITS DERIVATIVE: PEPTIDE BOND FORMATION, CHEMOSELECTIVE ACYLATION, AND BRIDGING REACTION
As a new extention of the monitored aminolysis of 3-acyl-l,3-thiazolidine-2-thione, its applications to peptidebondformation, chemoselective acylation of amino acid, and bridging reaction onthe enzyme model are reported.