Subfigure 1.1: Different parts of the polypeptide strand align with each other to form a β-sheet. This β-sheet is anti-parallel, because adjacent segments of the protein run in opposite directions. | Subfigure 1.2: β-sheets are sometimes referred to as β pleated sheets, because of the regular zig-zag of the strands evident in this representation. | Subfigure 1.3: Each segment in this representation represents a bond. Unlike the other two representations, side chains are illustrated. Note the alignment of oxygen atoms (red) toward nitrogen atoms (blue) on adjacent strands. This alignment is due to hydrogen bonding, the primary interaction involved in stabilizing secondary structure. |