Structural Biology
Structural biology is a branch of molecular biology concerned with the study of the architecture and shape of large biological molecules (macromolecules)-including proteins and nucleic acids (DNA and RNA) in particular. Structural biology examines the physical and chemical basis for the complex structures adopted these molecules. This subject is of great interest to biologists, because macromolecules carry out most of the functions of living cells. Typically, these functions depend on proteins, DNA and RNA adopting a specific three-dimensional shape. These shapes depend, in ways that can be predicted and measured, on the basic chemical structure of the molecules-specifically, on the amino acid sequence of proteins and on the nucleotide sequence of DNA or RNA.

Nuclear Magnetic Resonance Spectroscopy (NMR)
NMR is a technique for determining molecular structure, and can also be used to examine the changes that take place when molecules interact or bind to one another. The technique applies powerful external magnetic fields to align the nuclei of certain atoms and then measures the responses of those atoms when they are disturbed by electromagnetic radiation. Trained specialists can use the data gathered to deduce the precise structure and arrangement of molecules of interest, and the ways that their structure changes as they interact with one another.

Protein Folding and Stability
Protein folding refers to characteristic folded shapes adopted by proteins. Such shapes are consistent, stable and reproducible within living cells. Since proteins consist of chains of chemically linked amino acids, folding is determined by the amino acid sequence of the chains and by weak attractive and repulsive forces, and by strong chemical bonds, both within particular chains and between chains that bind together. Protein folding refers to the ways that the chains bend and bind together in three dimensions. The stability of a protein refers to its ability to retain the correct, native three-dimensional structure, as well as its resistance to degradation by enzymes or cellular processes.