SuperPose

SuperPose is a freely available web server designed to perform both pairwise and multiple protein structure superpositions. The “Structural superposition” term refers to the rotations and translations performed on one structure to make it match or align with another structure or structures. Structural superposition can be quantified either in terms of similarity or difference measures. The optimal superposition is the one in which the similarity measure is maximized (the former case) or the difference measure (the later case) is minimized. The “SuperPose” web server uses “RMSD” or Root-Mean-Square Deviation as a difference measure to find the optimal pairwise or multiple protein structure superposition. After an initial sequence and secondary structure (in case of low sequence identity) alignment, SuperPose generates a Difference Distance (DD) matrix from the equivalent C-alpha atoms of two molecules. The sequence/structure alignment and DD matrix analysis information is then fed into a modified quaternion eigenvalue algorithm to rapidly perform the structural superposition and calculate the RMSD between aligned regions of two macromolecules.