Speaker
Description
Abstract:
Proton transfer underlies enzymatic catalysis, ion transport, and energy conversion across biology, often involving short, strong H-bonds in which the proton is delocalized between two functional groups. Such low-barrier H-bonds (LBHBs) have been shown in protein active sites, but their dynamics are difficult to capture in this environment because LBHBs unfold on ultrafast timescales and with minor atomic rearrangement - the combination which is inaccessible to most structural methods. In my talk I present our recent high-resolution time-resolved serial femtosecond crystallography (TR-SFX) data collected at the Alvra station of SwissFEL on the light-driven Na+ pump ErNaR containing a functionally-relevant LBHB between two carboxylic residues and in direct interaction with its retinal Schiff base. This LBHB is identified by a characteristic infrared continuum band and is confirmed by proton and deuterium delocalization in quantum mechanics simulations. TR-SFX show the LBHB collapse in 600 ps of photon absorption by retinal, followed by microsecond-to-millisecond time scale rearrangements leading to the Schiff base deprotonation. I will also discuss how an ultrafast electronic event in the retinal cofactor is linked to a biological function occurring orders of magnitude later.
| Scientific Topics | Biology |
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