Estimate secondary structure from CD spectra :: the concentration independent Raussens et al method

This webserver allows you to estimate protein secondary structure from circular dichroism (CD) spectra using the method of:

Raussens V, Ruysschaert JM, Goormaghtigh E., (2003) "Protein concentration is not an absolute prerequisite for the determination of secondary structure from circular dichroism spectra: a new scaling method.", Anal Biochem., p114-21

The method is concentration independent, so it is particularily useful for getting a rough estimate in situations where determining an accurate protein concentration is hard (eg in the prescence of A280 and Bradford or BCA interfering detergents). The only input required is the CD signal at 193.0 nm, 196.0 nm, 207.0 nm (the point of normalisation), 211.0 nm and 234.0 nm. Since the analysis is independant of concentration (eg overall signal intensity), the units for the ellipiticity do not matter in this case. See the paper for more details, and feel free to browse my source code to check I didn't mess up the implementation.

Note that there was an erratum issued by the authors in Anal Biochem. 2006 Dec 1;359(1):150. This server uses the corrected equations, which change the estimates for alpha-helix and beta-strand compared with the originally published and erroneous method.

CD data:

Simple format (wavelength ellipticity) (example)
Aviv format
Jasco format (ascii text export, not the default save format) (example)

Other circular dichrosim analysis packages:

• The CDPro suite
• The K2D neural network secondary structure estimator
• Dichroweb - a web frontend to the CDPro tools and K2D (an excellent free service, but requires registration)