Chemistry Reference
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2
Introduction to Unnatural Foldamers
Claudia Tomasini and Nicola Castellucci
Dipartimento di Chimica “G. Ciamician”, Universit` di Bologna, Italy
2.1 General Definition of Foldamers
What is a foldamer?
The word “foldamers” was coined by Samuel H. Gellman in 1996 [1] to describe dis-
crete artificial oligomers that adopt specific and stable conformations similar to those seen
among proteins and nucleic acids. This neologism means “folding molecules” and refers
mainly to medium size molecules (about 500-5000 amu) that fold into definite secondary
structures (i.e., helices, turns and sheets), thus being able to mimic biomacromolecules
despite their smaller size. The essential requirement of a foldamer is to possess a well
defined, repetitive secondary structure, imparted by conformational restrictions of the
monomeric unit. Before the term “foldamer” was coined, many nucleic acid analogues
and peptide analogues had already been successfully designed to mimic the structures
and, potentially, the biological properties of their natural counterparts. Typical examples
are peptide nucleic acids (PNAs) [2] and N -substituted oligoglycines (peptoids) [3].
The path to creating useful foldamers involves several daunting steps.
1. One must identify new polymeric backbones with suitable folding propensities. This
goal includes developing a predicatively useful understanding of the relationship
between the repetitive features of monomer structure and conformational properties at
the polymer level.
2. One must endow the resulting foldamers with interesting chemical functions, by
design, by randomization and screening (“evolution”), or by some combination of
these two approaches.
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