Roles for Cavities in Protein Structure: New Insights

“Packing defects” which result in the presence of a cavity in the protein continue to be a subject of great interest. Naturally occurring or engineered cavities in the protein structure are empty or hydrated may depend on several factors (size, hydrophobicity, etc.) and is currently the subject of active debate. The role of protein cavities is considerable controversy and still needs further investigation. The presence of internal cavities appears to be crucial for conferring the conformational flexibility needed for their biological function. In several studies, stabilities of the protein could be improved by cavity filling mutations but concomitant loss of functionality, indicating their role in stability-function tradeoff. In this review, we hope to bring together the experimental studies available on protein cavities.