Small-molecule and macromolecular crystallography differ in the range of possible techniques used to produce diffraction-quality crystals. Small molecules generally have few degrees of conformational freedom, and may be crystallized by a wide range of methods, such as chemical vapor deposition and recrystallization. By contrast, macromolecules generally have many degrees of freedom and their crystallization must be carried out so as to maintain a stable structure. For example, proteins and larger RNA molecules cannot be crystallized if their tertiary structure has been unfolded; therefore, the range of crystallization conditions is restricted to solution conditions in which such molecules remain folded.
Small-molecule and macromolecular crystallography differ in the range of possible techniques used to produce diffraction-quality crystals Small molecules generally have few degrees of conformational freedom and may be crystallized by a wide range of methods such as chemical vapor deposition and recrystallization By contrast macromolecules generally have many degrees of freedom and their crystallization must be carried out so as to maintain a stable structure For example proteins and larger RNA molecules cannot be crystallized if their tertiary structure has been unfolded; therefore the range of crystallization conditions is restricted to solution conditions in which such molecules remain folded