Light induced charge and energy transport in nucleic acids and proteins: general discussion

Abstract

Amitabha Chattopadhyay opened the discussion of the paper by Gebhard F. X. Schertler: Do you have an idea of the timescale of the dynamics of these water molecules in GPCR structures? Gebhard F. X. Schertler replied: This depends on the water molecules that you are referring to. The water molecules close to the retinal will respond very fast. From looking at the time resolved measurements with bacteriorhodopsin, we know that it is faster than 16 nanoseconds. I expect it to be on the picosecond timescale. Water molecules in the hydrogen bond network connecting to the G protein binding site will rearrange in the same time frame as the conformational changes. In rhodopsin this ranges from microseconds to milliseconds. Richard Cogdell remarked: I agree that water molecules are important. Why do you think you would use water in this space rather than a larger amino acid? Water gives you a much greater structural exibility and a faster timescale. Do you think that is a reasonable way to think about it? Gebhard F. X. Schertler responded: As I pointed out, water molecules can have many roles inside a protein. I focused on the highly occupied water sites. This gives little information about the dynamics and exchange rates of the water molecules. It also does not mean that less ordered water molecules inside the protein are not important and so they could exist if the space allows it. I think you are implying

Unveiling the Role of Hidden Isomers in Large Stokes Shift in mKeima: Harnessing pH-Sensitive Dual-Emission in Bioimaging

“…A similar analysis is also performed at 590 nm by exciting the cis anionic form exclusively (Figure E and Table S6). With an increase in pH, the fluorescence lifetime of tryptophan increases which is consistent with previous observation of an increase in the quantum yield (Figure F). − A similar increase for the cis anionic form of the chromophore is observed at all excitations (i.e., at 295, 401, and 590 nm), which is likely due to the stabilization of the excited state (Figure F–H); a similar observation was also observed for a variant of the enhanced GFP (eGFP-pHsens) chromophore, rendering it a sensitive indicator for local pH . However, no definite trend is seen to be followed for the green emission from the cis neutral form of the chromophore (Figure G).…”