The term "side-chain theory" is commonly used in chemistry and biochemistry to describe the way in which the structure of proteins and other complex molecules is determined by the arrangement of their side chains. Synonyms for this concept might include "side-chain hypothesis," "side-chain model," or simply "side-chain theory." These alternative terms are useful when discussing the concept with others who may not be familiar with the original phrase, or when trying to emphasize a specific aspect of the theory. Regardless of the terminology used, understanding the importance of side chains in these complex molecules is key to unlocking their potential in fields such as drug discovery, materials science, and biomolecular engineering.