Analysis and prediction of inter-strand packing distances between {beta}-sheets of globular proteins

Any two ß-strands belonging to two different ß-sheetsin a protein structure are considered to pack interactivelyif each ß-strand has at least one residue that undergoesa loss of one tenth or more of its solvent contact surface areaupon packing. A data set of protein 3-D structures (determinedat 2.5 Å resolution or better), corresponding to 428 proteinchains, contains 1986 non-identical pairs of ß-strandsinvolved in interactive packing. The inter-axial distance betweenthese is significantly correlated to the weighted sum of thevolumes of the interacting residues at the packing interface.This correlation can be used to predict the changes in the inter-sheetdistances in equivalent ß-sheets in homologous proteinsand, therefore, is of value in comparative modelling of proteins.