Living cells consist of myriads of molecules. The large molecules, which include the proteins, interact with one another and with other molecules in a never-resting molecular machinery. How can we understand what is happening inside the cell? One important step is to develop
tools to "see" with. With mass spectrometry we can now quickly identify a substance in a sample by accurately determining its molecular mass. With NMR the three-dimensional structure of different substances can be studied. Unlike the alternative method, X-ray crystallography, NMR can be applied to molecules in solution.
This is a great advantage since the natural environment of the protein is the living cell. If one knows all the measurements of a house one can draw a three-dimensional picture of that house. In the same way, by measuring a vast number of short distances in a protein, it is possible to create a three-dimensional picture of that protein. As so often in biochemistry, form and function are intimately connected. By showing what the protein looks like at the atomic level, how it functions can also realised.