SINGULAR POINTS OF PROTEIN BETA-SHEETS

Protein beta-sheets can be regarded as surfaces. Two surfaces can be c onnected along a common edge to form a larger surface, or two edges of a surface can coalesce to form a closed sheet such as a beta-barrel. Singular points an locations where these connections are not perfect. In protein beta-sheets, a singular point is characterized by a residue separating two beta-ladders. In this paper, we study the singular poi nts of protein beta-sheets from the surface topologic viewpoint. summa rize our search results from the protein structural data in the Protei n Data Bank. and present examples where singular points are near the a ctive sites and may contribute to forming the proper relative position s of catalytic residues.