n→π* interactions in poly(lactic acid) suggest a role in protein folding.

Robert W Newberry, Ronald T Raines

Index: Chem. Commun. (Camb.) 49(70) , 7699-701, (2013)

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Abstract

Poly(lactic acid) (PLA) is a versatile synthetic polyester. We noted that this depsipeptide analog of polyalanine has a helical structure that resembles a polyproline II helix. Using natural bond orbital analysis, we find that n→π* interactions between sequential ester carbonyl groups contribute 0.44 kcal mol(-1) per monomer to the conformational stability of PLA helices. We conclude that analogous n→π* interactions could direct the folding of a polypeptide chain into a polyproline II helix prior to the formation of hydrogen bonds between backbone amides.