Chemistry Reference
In-Depth Information
11
Interaction of Biomimetic Oligomers
with Metal Ions
Galia Maayan
Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Israel
Metal ions are key elements in both the structure and function of natural biopolymers,
being employed in tasks spanning from structure stabilization to catalysis, light-energy
conversion and recognition. In the context of structure, metal ions can either stabilize an
existing structural fold or impose a conformational constraint on an unstructured poly-
peptide while facilitating its folding. The role of metal coordination in the folding of natu-
ral biopolymers, as well as the direct correlation between structure and function, inspires
the design of single-stranded biomimetic oligomers, namely peptidomimetics and their
abiotic analogues, that fold into three-dimensional structures upon metal binding. Unlike
helicates, in which metal ions template a helical structure via self-assembly, in bio-
mimetic oligomers metal ions nucleate the formation of a three-dimensional structure in a
controlled manner. Nucleation of a secondary structure is a great challenge because it
requires that metal ion coordination will initiate a series of cooperative, non-covalent
interactions in the molecular structure, leading to its folding. In this chapter, we will begin
with an introduction of biomimetic oligomers and describe their folding behavior. We will
show how metal ions can nucleate the folding of unfolded oligomers as well as stabilize
the existing secondary structures of biomimetic oligomers. Emphasis will be given to both
linear and cyclic systems in which absolute helicity can be achieved or enhanced through
a rational design of metallofoldamers. Next we will give some examples of systems in
which the folding induced by metal coordination leads to three-dimensional architectures
different from the helical structure, and we will end the chapter with conclusions and an
outlook for some future challenges.
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