Maybe low-spin, ferric cytochrome? 420 would be the soret peak and 520 the alpha+beta peaks which are very broad in the oxidized form. Add a little dithionite or ascorbate and see if the soret peak shifts to longer wavelength and the alpha peak sharpens up at 550-560 nm
Grishin, Andrey wrote:
Dear CCP4bb users, this problem was already discussed many times here and I've read these discussions before writing. I have a pale yellow protein. The spectrum contains peaks at 320 and 420. Before we proceed to ICP-OES and wavelength scans at the synchrotron, may be some of you had a similar spectrum before? Does not look like FAD, NADH and pyridoxal phosphate. Thank you Andrey Grishin Postdoctoral Fellow University of Saskatchewan
