32.19: Applications Of NMR In Biology

Nuclear magnetic resonance (NMR) spectroscopy is a very valuable analytical technique for researchers. It has been used for more than 50 years as an analytical tool. F. Bloch and E. Purcell formulated NMR in 1946 and won the 1952 Nobel Prize in Physics for their work. Biological macromolecules such as proteins, nucleic acids, lipids, and organic molecules including pharmaceutical compounds, can be studied using this versatile tool that exploits the magnetic properties of certain nuclei.

The basic principle of this technique is that nuclei, in addition to their electric charge, also have a spin. Nuclei with an odd atomic number or mass possess this property of spin, which is vital for the NMR technique. The spin is random and in random directions, similar to a spinning top. Hence, when placed under an external magnetic field, these nuclei align themselves with or against the applied field. These nuclei return to their original orientation when the external field is removed. The energy gap is then translated into a spectra that depends on the nature of the environment of the atoms, and the distance between nuclei. The resulting spectra helps study different parameters like the structure, dynamics, and properties of the samples. Properties such as reaction state,chemical environment, and interactions of the samples are examples of investigational results that can be studied with this technique.

In biology, ¹³C, ¹H, ²H ¹⁵N, ³¹P, ²³Na, and ¹⁹F are important biologically relevant NMR-active nuclei that help understand biochemical pathways involved in amino acid, lipid, and carbohydrate metabolism. Also, NMR offers a window into observing and quantifying numerous compounds in biological fluids, cell extracts, and tissues without the need for complex sample preparation or fractionation.

Over the past two decades, NMR has been developed to produce detailed images in a process now called magnetic resonance imaging (MRI), a name coined to avoid the use of the word “nuclear” and the concomitant implication that nuclear radiation is involved. MRI is based on NMR, in which an externally applied magnetic field interacts with the nuclei of certain atoms, particularly those of hydrogen (protons) of the body tissue.

Numerous applications of this technique, including its pivotal role in drug discovery and proteomics, are helping advance research to new heights, benefiting humanity.

Nuclear magnetic resonance or NMR spectroscopy is an analytical technique used to investigate the structure and composition of samples.

In biology, NMR has broad applicability; it is used to study proteins, lipids, and nucleic acids and even supports profiling complex metabolites.

An advantage of this technique is that it requires only a small amount of the sample.

NMR is particularly useful for determining the structure of proteins that are difficult to crystallize. It provides information on protein conformational changes, protein-ligand interactions, and how the protein folds inside a cell.

Non-invasive magnetic resonance imaging or MRI applies the NMR principle in medical diagnosis to take cross-sectional images of anatomical structures.

Magnetic resonance spectroscopy can compare the chemical changes in abnormal tissue, such as an Alzheimer’s patient’s brain tissue, with healthy brain tissue to study the metabolic changes during disease progression.

In pharmaceutical research, NMR allows the screening of potential drugs by determining the binding interaction between the drug and its target biomolecule.