Identification and characterization of molecules

Researchers involved in the discovery of novel bioactive natural products often have to identify the bioactive component present in the crude sample; for example, isolation of novel antibiotics and antimicrobial peptides from various organisms. Individual components in the crude sample are isolated based on the differences in their physical and chemical properties. The bioactive component is identified by testing the activities of these isolated compounds. The bioactive compound is then characterized using various spectroscopic methods to arrive at its structure and function(s). Bioanalytical techniques can typically be classified as shown in Figure 1.2.

Figure 1.2 Various bioanalytical methods

 

Spectroscopic tools such as infrared spectroscopy, circular dichroism spectroscopy, and nuclear magnetic resonance spectroscopy can provide structural information about the molecules which in turn provides insights into their functional aspects.

Studying biological processes

Life is an outcome of the complex interplay of biological molecules. These involve interactions between macromolecules (e.g. protein-protein interactions and DNA-protein interactions, RNA-protein interactions); interactions of biomolecules with small molecules (glucose channels, water channels, ligand-binding) and ions (K⁺ channel, Na⁺ and K⁺ pump, Ca²⁺ channels); and interaction of molecules with light (chlorophyll, photoreceptors). Interactions of the molecules with their receptors/ligands, both in vitro and in vivo, are usually studied using various spectroscopic and microscopic tools. Fluorescence spectroscopy and microscopy are among the most commonly employed tools to study the biological processes. Discovery of the green fluorescent protein (GFP) and subsequent development of its analogs with different spectral properties have revolutionized the area of cellular research. Before discussing in detail the various tools that have gained importance in bioanalytical research, it is worthwhile to take a pause for very quickly reviewing the important structural aspects of major classes of biomolecules.