The protein has 3 Tyr and 3 Phe and 0 Trp residues. It show a sharp peak at 365 nm corresponding to Phe and 3 peaks between 272 and 285 nm corresponding to Tyr but I am wondering what a positive peak at 305 means? The protein show a wonderful far-UV cd spectrum.
It may just be an artifact of the Cotton effect. The relevant data is below 300 nm and often times, published results only show windows from 190 nm to 300 nm
It's not an artifact. That implies that the CD is "wrong". Some obvious things to ask, is there something else bound to my protein that could cause that feature? If nothing else is apparent, one possibility is that it is the start of a very broad positive spectral feature caused by the disulfide bonds. The tryptophans must dominates the spectrum with a negative peak below 300nm, causing the apparent peak you see. If that is the case, it would be a very sensitive probe for changes in the dihedral angles of the disulfide bonds.
Thanks Lindsay for your valuable insight! This is a DNA-binding protein and have only one cysteine residue. It is found as a dimer and we are checking if it forms an inter-subunit disulfide bridge. As far as we can tell this is a pure protein with no DNA bound.
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry