91Ó°ÊÓ

Answer: The three key features of ligand-protein interactions are specificity and affinity, complementarity, and the induced-fit model. Specificity and affinity ensure that a protein can selectively bind to a particular ligand with the appropriate strength, which determines the overall function of the protein. Complementarity involves the matching of shapes and properties between the protein binding site and the ligand, ensuring that only the appropriate ligand can bind, thus maintaining specificity and proper function. The induced-fit model describes how proteins can undergo conformational changes upon ligand binding to ensure optimal binding, which can influence various biological processes and modulate the protein's activity.