Interfacial molecular recognition and chirality in amphiphilic assemblies
In nature, interfacial molecular recognition and chirality are of fundamental significance for the construction of biological assemblies. Biological receptors are situated at interfaces of supramolecular biological systems at which specific molecular recognition processes occur.
Chiral objects are abundant in nature and are operative in many biological systems at both microscopic as well as macroscopic levels. Ordinary chiral examples are proteins and their constituent amino acids, nucleic acids and their constituent sugars as well as membranes and their constituent lipids and membrane proteins. However, these biological units loose their functionality when their chiral structures are altered. In most cases, only one enantiomer is biologically active. The small energy difference between the two enantiomeric forms results in a further challenge to understand the well-known problem of homochiral evolution in nature.
Understanding the reason for chiral preference in nature is also of practical importance. At present, single-enantiomeric drugs constitute more than 30% of the total therapeutic drugs and constitute more than 50% of total sales in particular classes such as, cardiovascular, antibiotics and antifungals, hormones, cancer and haematology related drugs. The annual sales of single-enantiomer drugs exceed $US 100 billion.
The reviews of this section represent recent advances in current aspects of interfacial molecular recognition and chirality. The field of interfacial molecular recognition and chirality in amphiphilic assemblies encompasses many orders of magnitude in scale and complexity, ranging from fundamental model studies at liquid and solid interfaces to attempts to describe the origin of life.
Over the recent years, different aspects have been studied how life can emerge. In an attempt to understand the origin of life, H. Kuhn discusses by logical considerations and on the basis of physics and chemistry, why and how a machinery like life's genetic apparatus can emerge in a stochastic process. According to this view, the basic organizational structure of the machinery emerges by necessity when appropriate prebiotic conditions occur. Kuhn considers only the very first steps, at the beginning of which a particular prebiotic chemistry allows the formation of appropriate monomers and corresponding oligomers. Correspondingly, a strand can be formed that must be homochiral to allow precise interlocking between template and a growing replicate. According to Kuhn's model, a break of symmetry has taken place on earth and this first casual event determines the chirality of all life.