Why structural biology?
Structural biology is a research field that tries to answer biological questions by determining 3D structures of biological molecules, including proteins and nucleic acids. The structure information of these molecules is very powerful, so they can answer many biological questions.
Biological molecules, especially proteins, have unique 3D structures that determine their functions. The reason why drugs work is because of this. Drugs tightly bind to unique shapes of cleaves of proteins created by their complex 3D structures and stop signal cascades. For instance, if you have headache, you take pain killers, which bind to proteins that mediate signal cascades causing headache. Drugs compete with cellular molecules that are supported to mediate pain signals by binding to target proteins. Signals stop if the molecules cannot bind the proteins, so you don't feel pain. Drugs and cellular molecules have complementary shapes to cleaves of target proteins. Shapes of cleaves are different among proteins; therefore, we can specifically target specific proteins by drugs. Therefore, knowing 3D structures of proteins is a great advantage for drug design because we need to design chemicals complementary to the shapes of cleaves of target proteins. Without knowing the structures, we just need to screen many chemicals.
In addition to drug design, the 3D structure of biological molecules provides beneficial information for research. For instance, you can introduce mutations to abolish protein-protein interactions without disrupting 3D structures of proteins to study the interactions' nature. "Without disrupting 3D structures" is key. Proteins tend to have more than one function. If you utterly destroy target proteins by disrupting their 3D structures, you observe complex phenotypes caused by losing different functions. However, people sometimes want to study a specific function of a protein. Then, they can use 3D structures to know how to abolish the function by mutating a particular residue. Related to this topic, many inherited mutations causing diseases result from one mutation in one gene. With 3D structures, people can explain why such mutation causes disease.
