logo.gif (3296 bytes)Introduction to Protein Structure

Secondary Structure -- Beta Sheet

The backbone of an beta sheet (shown in color below) is arranged in zig-zag (or pleated fashion. Notice how the sidechains (shown in dark grey) stick from the backbone on each side of the sheet.The example show below is a three stranded beta sheet. A minimum of two strands is required to define a beta sheet; many beta sheets have more.

The beta sheet is stabilized by hydrogen bonds between the carbonyl oxygen of an amino acid in one strand and the backbone nitrogen of a second amino acid in another strand. Beta sheets can be either parallel or anti-parallel.  If the amino terminal residue of each strand "points" in the same direction the sheet is considered parallel. Anti-parallel sheets have the amino termini "pointing" in opposite directions.   Turn on the "highlight" in the figure below to color the amino terminal residue of each strand.




This beta sheet consists of residues 42-46, 49-54 and 56-60 in chicken egg white lysozyme.

Copyright 1998, 1999, 2007 by Frank R. Gorga;   Page maintained by F.R. Gorga;   Last updated: 12-Mar-2007