The synthesis of well-defined polypeptides based on the ring opening polymerization of a-amino acid-N-carboxyanhydrides (NCAs) has attracted synthetic chemists since the early 20th century. In the last decades various techniques to control the polymerization have emerged focusing on lower dispersities.1 Polylysine has been applied to a variety of applications like coatings for improved cell attachment or in gene delivery.2In this work, two series of polylysines with Z and TFA protecting groups were synthesized and their behavior in a range of analytical methods was investigated. GPC of the smaller polypeptides reveals a bimodal distribution, which is lost in larger polymers. With the help of GPC, NMR, CD and MALDI-TOF it has been demonstrated, that this bimodal distribution is not due to terminated chains but a change in secondary structure of the growing peptide chain occuring around DP=15.The two different secondary structures can be separated and analyzed individually. This work shows that secondary structures need to be carefully considered in synthesis and characterization of polypeptides.(1) Deming, T. J. Nature 1997 , 390, 386�389; N. Hadjichristidis, H. Iatrou, M. Pitsikalis, G. Sakellariou, Chem. Rev. 2009 , 109, 5528�5578; Conejos-S�nchez, I.; Duro-Castano, A.; Birke, A.; Barz, M.; Vicent, M. J. Polym. Chem. 2013 , 4, 3182�3186.(2) Mazia, D. J. Cell Biol. 1975 , 66, 198�200; Christie, R. J.; Nishiyama, N.; Kataoka, K. Endocrinology 2010 , 151, 466�473.

Influence of secondary structure on polypeptide synthesis and characterization

247th National Meeting (2014)

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