Background: Now-a-days, drug design is an important area of research in medicinal chemistry
and theoretical aspects of it basically involve molecular docking. Therefore, a detailed knowledge of
drug targets, de facto of proteins/enzymes, is essential and thus it has created interest in the study of
protein structure and its flexible nature.
Objective: The article aims to describe in detail the flexible nature of proteins and its implication in
Method: A detailed survey of the studies on protein flexibility has been made and critically reviewed.
Results: Proteins have been found to possess conformational flexibility. They possess an ensemble of
conformations. Now the theory of protein-ligand binding has greatly shifted from lock-and-key model
to induced-fit model. Since the current concept assumes that protein can exist in many conformations, a
ligand can bind to any conformation depending upon its shape and size and thus ligand of any size can
be considered to interact with the protein.
Conclusion: Protein flexibility stands out to be one of the most important and challenging issues for
binding and discovering the potent drugs. Proteins may possess several conformations, but to study the
nature of the binding site in them, one must consider its binding partner. Thus, only that conformation
of protein is involved in the binding in which the structure of binding site is complementary to that of