Asano, Akiko published the artcileEffect of the powerful plasticity of the tert-butyl side chain on the conformational equilibrium of ascidiacyclamides, Synthetic Route of 106391-88-2, the publication is Journal of Peptide Science (2021), 27(12), e3363, database is CAplus and MEDLINE.
Ascidiacyclamide [cyclo(-Ile1,5-oxazoline2,6-D-Val3,7-thiazole4,8-)2] is a cytotoxic cyclic peptide from ascidian. Through structural analyses using monosubstituted analogs (Xaa1: Ala, 2-aminobutyric acid, Val, cyclohexylglycine, and phenylglycine), we previously demonstrated the conformational equilibrium between its square and folded forms. As the bulkiness of the Xaa1 residue side chain was reduced, spontaneous folding was promoted, and the cytotoxicity decreased accordingly. In the present study, five disubstituted analogs in which a tert-leucine residue (Tle) was incorporated at the 5-position of the abovementioned monosubstituted analogs were synthesized, after which their structures were analyzed using X-ray diffraction, CD (CD) spectral measurements, and 1H NMR-based quant. anal. The side chains of the Tle and Ile residues are structural isomers of one another, and the Tle residue bearing the tert-Bu group can be expected to play a role as a building block. In fact, peptides incorporating Tle5 exhibited much less spontaneous folding than their Ile5 counterparts in both crystal and solution Increases in enthalpy and entropy due to the tert-Bu group during the folding process resulted in increased conformational free energy (ΔG°). The powerful plasticity of the tert-Bu group would stabilize the square form relating with cytotoxicity.
Journal of Peptide Science published new progress about 106391-88-2. 106391-88-2 belongs to esters-buliding-blocks, auxiliary class Amine,Aliphatic hydrocarbon chain,Amide,Aldehyde, name is (R)-tert-Butyl (3-methyl-1-oxobutan-2-yl)carbamate, and the molecular formula is C10H19NO3, Synthetic Route of 106391-88-2.
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