Murase, Sara K.; Haspel, Nurit; del Valle, Luis J.; Perpete, Eric A.; Michaux, Catherine; Nussinov, Ruth; Puiggali, Jordi; Aleman, Carlos
Molecular characterization of L-phenylalanine terminated poly(L-lactide) conjugates
RSC ADVANCES, 4:23231-23241, 2014

Peptide-polymer conjugates made of poly(L-lactide) and L-phenylalanine or L, L-diphenylalanine (F-PLA and FF-PLA, respectively) have been synthesized by the ring-opening polymerization of L-lactide using the peptide fragment as an initiator. The structure of the conjugates was confirmed by H-1 NMR, FT-IR, GPC, UV-Vis and CD. Molecular dynamics simulations have been used to identify both the conformational preferences of the FF-PLA conjugate in solution and the potential intramolecular interactions between the peptide and polymer blocks, while TD-DFT calculations have been applied to model the electronic transitions observed by the UV-Vis absorption spectroscopy. Results show that the polymer fragment prefers a random coil or a mix of helix/strand while the peptide fragment tends to have folded and helical conformations. Although the degree of interaction between the two fragments is slightly higher than that reported for other peptide-polymer conjugates, it is small enough to suggest that FF-PLA is a potential candidate to aggregate forming peptide-guided organizations via self-assembly. On the other hand, quantum mechanical calculations have allowed us to identify the pi -> pi* transition, which is typically observed in helical peptides and proteins, as well as the n -> pi* transition along the N-C-O backbone.

DOI:10.1039/c4ra01534g

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