α-helix to random coil transitions: Determination of peptide concentration from the CD at the isodichroic point

✍ Scribed by Marilyn Emerson Holtzer; Alfred Holtzer

• Publisher: Wiley (John Wiley & Sons)
• Year: 1992
• Tongue: English
• Weight: 305 KB
• Volume: 32
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360321209

✦ Synopsis

A method is presented for determining the concentrations of peptides and proteins having isodichroic points near 203 nm. The existence of an isodichroic point for a given substance indicates a local two-state (a-helix, random coil) population. The mean residue ellipticity at the isodichroic point, [Ox, 1, is, of course, independent of helix content. For a wide variety of synthetic and natural peptides, including both single helices and coiled coils, it is shown that [Ox, ] is also essentially independent of substance and of whether the transition is