Proteins 2

Table of Contents
Biomolecules Gateway Page
Jmol Tutorial

In this module:

Secondary Structure
α Helices
ß Sheets
Tertiary Structure
Disulfide Bonds, Domains
Cofactors, Quaternary Structure
Protein Folding
Alzheimer's and "Mad-Cow" Diseases


α helices and ß sheets combine to form motifs that have common functions and are found in many proteins. Some examples are shown below.

The helix-turn-helix motif shown here is called an EF hand. This structure is often used to bind metal ions (like the Ca2+ ion shown here) and hold them in a specific orientation.

α helices often pack against each other at angles of +20 or -50º, so that the ridges of one can fit into the grooves of another.

The strands of a parallel ß sheet are often linked by an α helix in a ßαß motif.

Several ß strands together can form a ß barrel.