Tight Asp-85–Thr-89 association during the pump switch of bacteriorhodopsin

Hydrogen Bonds of Protein‐Bound Water Molecules in Rhodopsins

“…The strong hydrogen bond of water402, whose OÀD stretching frequency is at 2171 cm À1 , is highlighted in BR, L and M. The hydrogen-bonding acceptor is Asp85 in BR and L, but switched to Asp212 in M. In this model, the hydration switch of water402 from Asp85 to Asp212 is correlated with a proton transfer from the Schiff base to Asp85. The interaction of Thr89 and Asp85 is from our FTIR results [22,23]. The orientation of the NÀD group in K is from a theoretical calculation [30], which is consistent with our FTIR results [24].…”

Crystal Structure of the M Intermediate of Bacteriorhodopsin: Allosteric Structural Changes Mediated by Sliding Movement of a Transmembrane Helix

“…Unfortunately, their results are not well correlated with diffraction and spectroscopic data from purple membrane. 41,45 One possible reason for the discrepancy between the diffraction data from the P6 3 crystal and those from purple membrane is that the lattice force affects the magnitude of conformational change. In the P6 3 crystal, the proteins are packed so densely that light-induced structural changes (e.g.…”

A light-driven sodium ion pump in marine bacteria

“…This indicates that H30 in A-helix is required for proton pumping, which is presumably located in the hydrogen-bonding network. Functionally important residues of KR2 such as R109, N112, D116 and D251 are also important for other microbial rhodopsins (R82, D85, T89 and D212 in BR) 26,[36][37][38] , whereas H30 is a unique residue in KR2. Interestingly, H30A pumps the sodium ion, but its binding signal is unclear (Fig.…”