Chemistry Reference
In-Depth Information
CHAPTER 2
MOLECULAR RECOGNITION USING
AMPHIPHILIC MACROMOLECULES
MALAR A. AZAGARSAMY, K. KRISHNAMOORTHY, and
S. THAYUMANAVAN
2.1. INTRODUCTION
Molecular recognition in living systems, which is responsible for function and
malfunction or dysfunction, involves macromolecular scaffolds as the recognition
partners. The macromolecules that Nature uses for this purpose involve proteins
or nucleic acids. Nature uses noncovalent interactions such as hydrogen bonding,
electrostatic attraction, metal -ligand binding, hydrophobic, and p-p interactions
for recognition events. Most of these noncovalent interactions are quite nonspecific
by themselves. However, Mother Nature has solved this issue by invoking
multivalent interactions using a combination of the above interactions. Of more
importance, when macromolecular scaffolds are used in Nature, a combination
of the interaction features are precisely placed in three-dimensional space in
order to be specific to the recognition partner for which these have evolved.
Supramolecular chemists have been interested in mimicking the recognition events
in nature (Cram 1988; Philp and Stoddart 1996; Wallimann et al. 1997; Zeng and
Zimmerman 1997; Davis and Wareham 1999; Mueller-Dethlefs and Hobza 2000;
Adams et al. 2001; Prins et al. 2001; Hof et al. 2002; Sun et al. 2002; Lehn 2005;
Hannon 2007; Oshovsky et al. 2007). It is interesting, however, that most of the
custom-designed systems for this purpose involve small molecule mimics, which
rarely capture the essence of the complexities in biological systems. In contrast,
when designing large macromolecules (polymers), synthetic methodologies are
simply not available to match the efficiency of the cellular synthetic machinery
that can program the assembly of a complex protein with a specific sequence.
Moreover, we are only beginning to understand the factors that control the folding
