Secondary Structure

For many decades, the most prevalent application of Circular Dichroism spectroscopy has been the quantification of secondary structure in polypeptides. To this end, far-UV CD data are subjected to secondary structure decomposition analysis, which yields estimates for the fractional amounts of different secondary structure elements in the peptide or protein of interest. Usually, the results are expressed in percentages and always include at least numbers for helices, sheets, turns, and random coil secondary structure. But what exactly are these?

Explore a gallery of more than five dozen protein structures below to learn about secondary structure elements, and create a small peptide in our playground further below to gain a better understanding of the underlying principles of secondary structure classification.

After spending some time on this page, you will be able to appreciate that secondary structure is not just about a-helices and ß-sheets!

Note: Some of the content below is simplified and goes without claim to be a replacement for existing literature. Please see the references provided for more detailed information.