scholarly journals Ultrafast Backbone Protonation in Channelrhodopsin-1 Captured by Polarization Resolved Fs Vis-pump—IR-Probe Spectroscopy and Computational Methods

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 848 ◽  
Author(s):  
Till Stensitzki ◽  
Suliman Adam ◽  
Ramona Schlesinger ◽  
Igor Schapiro ◽  
Karsten Heyne

Channelrhodopsins (ChR) are light-gated ion-channels heavily used in optogenetics. Upon light excitation an ultrafast all-trans to 13-cis isomerization of the retinal chromophore takes place. It is still uncertain by what means this reaction leads to further protein changes and channel conductivity. Channelrhodopsin-1 in Chlamydomonas augustae exhibits a 100 fs photoisomerization and a protonated counterion complex. By polarization resolved ultrafast spectroscopy in the mid-IR we show that the initial reaction of the retinal is accompanied by changes in the protein backbone and ultrafast protonation changes at the counterion complex comprising Asp299 and Glu169. In combination with homology modelling and quantum mechanics/molecular mechanics (QM/MM) geometry optimization we assign the protonation dynamics to ultrafast deprotonation of Glu169, and transient protonation of the Glu169 backbone, followed by a proton transfer from the backbone to the carboxylate group of Asp299 on a timescale of tens of picoseconds. The second proton transfer is not related to retinal dynamics and reflects pure protein changes in the first photoproduct. We assume these protein dynamics to be the first steps in a cascade of protein-wide changes resulting in channel conductivity.

2006 ◽  
Vol 110 (47) ◽  
pp. 12805-12813 ◽  
Author(s):  
V. C. Felicíssimo ◽  
F. F. Guimarães ◽  
A. Cesar ◽  
F. Gel'mukhanov ◽  
H. Ågren

2018 ◽  
Vol 9 (15) ◽  
pp. 4174-4181 ◽  
Author(s):  
Zhuoran Kuang ◽  
Qianjin Guo ◽  
Xian Wang ◽  
Hongwei Song ◽  
Mark Maroncelli ◽  
...  

2005 ◽  
Vol 122 (9) ◽  
pp. 094319 ◽  
Author(s):  
V. C. Felicíssimo ◽  
F. F. Guimarães ◽  
F. Gel’mukhanov ◽  
A. Cesar ◽  
H. Ågren

2015 ◽  
Vol 71 (7) ◽  
pp. 539-544 ◽  
Author(s):  
Mohammad Ghadermazi ◽  
Jafar Attar Gharamaleki ◽  
Marilyn M. Olmstead ◽  
Mehdi Almasi

The reaction of the proton-transfer compound piperazine-1,4-diium pyrazine-2,3-dicarboxylate 4.5-hydrate, C4H12N22+·C6H2N2O42−·4.5H2O or (pipzH2)(pyzdc)·4.5H2O (pyzdcH2is pyrazine-2,3-dicarboxylic acid and pipz is piperazine), (I), with Zn(NO3)2·6H2O and CoCl2·6H2O results in the formation of bis(piperazine-1,4-diium) bis(μ-pyrazine-2,3-dicarboxylato)-κ3N1,O2:O3;κ3O3:N1,O2-bis[aqua(pyrazine-2,3-dicarboxylato-κ2N1,O2)zinc(II)] decahydrate, (C4H12N2)2[Zn2(C6H2N2O4)4(H2O)2]·10H2O or (pipzH2)2[Zn(pyzdc)2(H2O)]2·10H2O, (II), andcatena-poly[piperazine-1,4-diium [cobalt(II)-bis(μ-pyrazine-2,3-dicarboxylato)-κ3N1,O2:O3;κ3O3:N1,O2] hexahydrate], {(C4H12N2)[Co(C6H2N2O4)2]·6H2O}nor {(pipzH2)[Co(pyzdc)2]·6H2O}n, (III), respectively. In (I), pyzdcH2is doubly deprotonated on reaction with piperazine as a base. Compound (II) crystallizes as a dimer, whereas compound (III) exists as a one-dimensional coordination polymer. In (II), two pyzdc2−groups chelate to each of the two ZnIIatoms through a ring N atom and an O atom of the 2-carboxylate group. In one ligand, the adjacent 3-carboxylate group bridges to a neighbouring metal atom. A water molecule ligates in the sixth coordination site. The structure of (II) can be described as a commensurate superlattice due to an ordering in the hydrogen-bonded network. In (III), no water is coordinated to the metal atom and the coordination sphere is comprised of twoN,O-chelates plus two bridging O atoms. A large number of hydrogen bonds are observed in all three compounds. These interactions, as well as π–π and C=O...π stacking interactions, play important structural roles.


1992 ◽  
Vol 70 (6) ◽  
pp. 1640-1644 ◽  
Author(s):  
Enric Bosch ◽  
Miquel Moreno ◽  
José M. Lluch

Abinitio self-consistent field (SCF) calculations were done for a model of a ribonucleoside where only the ring part of the furanoside form of D-ribose is considered. Full geometry optimization and direct location of stationary points were used in order to characterize the geometry of the minimum energy structure and of the transition state for the proton transfer reaction in the anion. Topological analysis of the charge density and its Laplacian for the minimum energy structure allow us to find clear electronic and geometrical evidence of an intramolecular hydrogen bond. On the other hand, our results show a very low energy barrier for the proton transfer so that the proton jumps easily between the two oxygen atoms.


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