【正文】 of New Jersey 2,San Diego Superputer Center (SDSC) 3,Center for Advanced Research in Biotechnology (CARB) What information dose PDB contain ? A variety of information associated with each structure is available, including sequence details, atomic coordinates, crystallization conditions, 3D structure neighbors puted using various methods, derived geometric data, structure factors, 3D images, and a variety of links to other resources. Folds? Mixed AlphaBeta Barrel Mainly Alpha Orthogonal Bundle Mainly Alpha Alpha/Alpha Barrel Images taken from CATH Since the two welldefined secondary structural units of helices and sheets are abundant in proteins, families of protein structures have been classified by a system based upon the alphahelix and beta sheet and their general topological properties. Each different topology may be considered as a fold. Current thinking suggests that there are a limited number of folds found in naturally occuring proteins.: AllAlpha folds, in which the secondary structure is almost exclusively alphahelical AllBeta folds, in which the secondary structure is posed almost exclusively of betasheets Alpha/Beta f