1
|
I have an aromatic spectrum of Tyr residues in p53 DNA binding domain. No peaks are seen for Tyr-205 at high temp, but as temp decreases 4 peaks are shown. Tyr-163 and Tyr-236 show two peak each at high temps. How come there aren't 4 peaks? The dynamic processes are said to occur on different time scales. What is the interpretation of this information? How is the core domain of p53 influenced by this? Thanks for your help! |
|
1
|
Is this a 1H spectrum? This could be a classic case of aromatic ring flips and slow vs. fast exchange. In the general case at low temp the different evironments of the C2H and C4H (delta H), and the C3H and C5H (epsilon H) protons are in formally different environments and give non-degenerate chemical shifts (so four peaks in all). As the temperature is raised the increased rate of the 180-degree ring flips (along the C1-C4 axis) lead to averaging of the chemical environments and line broadening and eventual collapse (in the fast exchange limit) to a single exchange-averaged chemical shift for each pair (so two peaks in total). In most proteins one observes fast exchange for most Tyr residues. Only a few Tyr (or Phe) residues ever exhibit true slow exchange and then only at relativly low temperatures. This was famously all worked out for the case of BPTI by Wuthrich and Wagner many years ago. |
