Different Flavours of Fragments

Fragment has been in the pharma vocabulary for around 20 years. To most medicinal chemists the word means fragment-based drug discovery (FBDD), but from an academic perspective it can be much broader and it can range from trying to identify substrates for orphan proteins to understanding binding interactions involved in riboswitch regulation. Even within drug discovery the approach to FBDD can vary significantly in terms of library size, and screening techniques. The roles for fragments are also expanding. They have now been used in assessing druggability, identifying hotspots on protein surfaces, finding allosteric pockets etc. In this chapter we will briefly give a perspective on these different flavours of fragments, starting with the most well understood in FBDD.