56777-25-4

Upstream product

• 100-39-0 benzyl bromide 
• 15761-38-3 L-N-Boc-Ala 
• 56777-24-3 benzyl (S)-Lactate 

Relevant academic research and scientific papers

Modifying oligoalanine conformation by replacement of amide to ester linkage

Oligo(lactic acid) is an ester-analogue of short oligoalanine sequence and adopts a rigid left-handed helical structure. In this study, oligo(lactic acid) was incorporated into oligoalanine sequences and their conformations were studied by vibrational circular dichroism and electronic circular dichroism spectroscopy. The results suggested that oligo(lactic acid) moiety in these sequences maintains a left-handed helix and increases the conformational propensity of the oligoalanine moiety to form a left-handed polyproline type II-like helix. The importance of the chirality of oligo(lactic acid) moiety for the oligoalanine conformation was also studied. The results obtained in this study should be useful in developing ester-containing oligopeptides that function better than normal peptides.

PHOSPHORAMIDATE NUCLEOSIDE PRODRUG FOR TREATING VIRAL DISEASES AND CANCER, PROCESSES FOR THEIR PREPARATION AND THEIR USE

The present invention pertains to chemotherapeutic agents and their use for treating viral and cancerous diseases. These compounds are inhibitors of HCV NS5B polymerase, HBV DNA polymerase and, HIV-1 reverse transcriptase (RT) inhibitor, and for treatment

Hydrogen-bond-mediated folding in depsipeptide models of β-turns and α-helical turns

The folding of several depsipeptides constructed from α-amino acids [L-proline (P) and L-alanine (A)] and α-hydroxy acids [L-lactic acid (L) and glycolic acid (G)] has been examined in methylene chloride solution by variable- temperature IR spectroscopy. Additional studies have been conducted in some cases, involving variable-temperature 1H NMR spectroscopy and molecular mechanics calculations. The depsipeptides include three-residue molecules (PLL, ALL, and PLG) that can form a 13-membered-ring amide-to-amide hydrogen bond, which, for a peptide backbone, would correspond to a single turn of an α-helix. These depsipeptides can also form 10-membered-ring amide-to-ester hydrogen bonds, which would correspond to β-trun formation for a peptide backbone. For PLL and PLG, distinct N-H stretch bands can be identified for three folding patterns: non-hydrogen-bonded, β-turn, and α-helical turn. IR-based van't Hoff analyses for PLL indicate that the α-helical turn and the β-turn are both modestly enthalpically favored relative to the non-hydrogen-bonded state, but neither turn is enthalpically preferred over the other. For PLG, in contrast, the α-helical turn appears to be enthalpically preferred over both of the alternative folding patterns. Comparison between PLL and ALL indicates that the N-terminal proline residue favors α-helical turn formation. The strengths of amide-to-amide and amide-to-ester hydrogen bonds have been compared in the context of a β-turn geometry by analyzing LG and AG in CH2Cl2. The amide-to-amide hydrogen bond is enthalpically favored by ca. 1.6 kcal/mol, but formation of this enthalpically stronger intramolecular hydrogen bond is more costly entropically. Extrapolation from the behavior of these depsipeptides leads us to predict that for tripeptides in a nonpolar environment, a β-turn will generally be enthalpically preferred over an isolated α-helical turn. β-Turn folding has previously been widely studied in model peptides and depsipeptides; however, the present report appears to represent the first experimental effort to model formation of a single α-helical turn.