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Proteins are the primary molecular machines of biological systems. They are widely studied in terms of both structure and function. Proteins fold into specific three-dimensional (3D) structures, which are determined by their amino acid sequences. Protein conformation is usually defined as the spatial arrangement of its constituent atoms, which determine the overall shape of the macromolecule. However, proteins are not rigid molecules; they change their conformations rapidly in a solution linked to their biological functions. Some of the most striking examples of protein dynamics and conformational changes include protein folding and unfolding, catalysis, mediation of cell motility, transport through membranes, cell replication, transcription and translation, and assembly and disassembly of protein complexes in general.

Different conformational changes resulting from the intrinsic flexibility of a protein are linked to particular energy levels and timescale, for example, protein dynamics, where the backbone of a protein is involved, is observed during protein folding. During protein folding, the global conformational changes are introduced by the rotation around the dihedral angles around the planer peptide bond and associated side-chain reorientations. On the other hand, some localized changes with reorientations of a few residues and small torsional changes in a particular region of the main chain can also be observed during many biological phenomena like enzyme catalysis, signaling, etc. Dynamic and thermodynamic properties of a protein are encoded in the protein sequences that can be modified through gene mutations during biological evolution according to the biological function the protein is destined to perform. The relationship between protein flexibility and function has been extensively studied; for example, in P53, high flexibility is a prerequisite for signaling regulation. Another example is microorganisms that survive in extreme environments; proteins and enzymes isolated from these microorganisms are functional and stable under extreme conditions. This is due to gene mutations that modify the structural dynamics of enzymes and shift the active conformation distribution curve to extreme conditions.