Protein and Peptide Interactive Terminal

Please paste or type your protein sequence into the area below.
Select the calculation you wish to perform and click " Calculate! "

Protein's Name:

Please select the type of analysis:

Hydropathy Plot (Kyte-Doolittle)
Titration Curve
Parameters (MW, pI, AA Comp, Extinction Coeff*.)
Draw this sequence as a membrane protein
UV Spectrum prediction*

*Recently, a colleague from Lunds university pointed out that the extinction coefficients from the paramater calculation and those from the spectrum prediction are different. Here's why:
The parameter algorithm uses the following simple equation to predict the extinction at 280 nm:

A = 5690 * #Trp + 1280 * #Tyr + 60 * #Cys

The UV spectrum prediction program models a Gaussian curve around the various transitions; (following with their maxima):

Cys-Cys: 250 nm
Phe: 257 nm
Tyr - OH: 274 nm
Tyr - ring: 222 nm
Trp - indole: 280 nm
Trp - ring: 219 nm
His - imid.: 211 nm
Peptide bonds: 211 nm

The contributions are summed to predict an absorbance at each wavelength - including the extinction at 280 nm. I'm not sure which one is more accurate in the real world, but if any one knows, please comment.
Thank you to Dr. Groening and others for reporting possible bugs. Keep them coming!