Biochemistry

Biochemistry is the study of chemical processes in living organisms. It covers a wide range of topics from the structure and function of biomolecules, to the regulation of metabolism, to molecular genetics. Biochemists use a variety of techniques, including X-ray crystallography, nuclear magnetic resonance spectroscopy, and mass spectrometry, to investigate the structure and function of biomolecules.

A central goal of biochemistry is to understand how cells work. All cellular activities — from metabolism to gene expression — are carried out by proteins. Proteins are large molecules made up of amino acids, which are themselves small molecules. The sequence of amino acids in a protein determines its three-dimensional structure, and this structure determines its function.

In order to carry out their functions, proteins must interact with other molecules in the cell. These interactions often involve enzymes — proteins that catalyze chemical reactions — binding to their substrates (the molecules on which they act). Enzymes can be very specific: some enzymes bind only one substrate, while others bind multiple substrates or even whole complexes of molecules. In addition to enzymes, proteins can also interact with small molecule ligands (such as hormones) or with other proteins (in what are called protein-protein interactions).

All these protein-ligand interactions are mediated by the three-dimensional structure of the proteins involved. Proteins can change their shape in response to changes in their environment; for example, when an enzyme binds its substrate, it may undergo a conformational change that brings active sites into close proximity so that catalysis can occur more efficiently. A detailed understanding of how these structural changes lead to changes in function is one major focus of biochemistry research today.