Three-dimensional structures of proteins are the support of their biological functions.Their folds are stabilized by contacts between residues.Inner protein contacts are generally described through direct atomic contacts, while contact prediction methods mainly used inter-C distances. During the process of protein folding, the amino acid residues along the polypeptide chain interact with each other in a cooperative manner to form a stable native structure.The knowledge about inter-residue interactions in protein structures is helpful to understand the mechanism of protein folding and...