Grotthuss mechanism of proton translocation
The Grotthuss mechanism is a proposed way for protons to cross a membrane protein by passing charge along linked water molecules, not by carrying one particle the whole way. Spikes and colleagues invoke it for ATP synthase's inlet half channel5. Morelli and colleagues discuss it for cytochrome c oxidase4. It matters because respiratory proton pumping builds the gradient that drives ATP synthesis6.
- Earliest held
- 1915, Bayliss, W. M.
- Most discussed in
- An update of the chemiosmotic theory as…, 2019
- In the library
- 40 passages in 13 works
- Rewritten
- 2026-11-01
A name with two uses
The name Grotthus is also attached to a rule in photochemistry. Bayliss, in Principles of General Physiology (1915), credited Grotthus (1819) with the first clear statement that light must be absorbed to produce an effect1. Bayliss added that Draper stated it independently at a later date. The rule is frequently called Draper's law1.
The proton pumping problem
Wallace (2013) described electrons passing through complexes I, III and IV, with the released energy used to pump protons across the inner membrane. Brzezinski and colleagues (2021) described the same current as driving translocation from matrix to intermembrane space, which maintains a protonmotive force6. Kühlbrandt (2015) noted that how electron transfer is coupled to proton translocation in complex I was still unknown2.
Evidence in ATP synthase
Spikes, Montgomery and Walker (2020) reported atomic models of dimeric bovine ATP synthase. They said the models provide evidence for a Grotthus mechanism in the inlet half channel of the membrane domain5. Their keywords list a Grotthus chain5. Nunn, Guy and Bell (2022) cited recent data for an ordered water channel in ATP synthase that could channel protons by this route7. They also said ordered water has been inferred in the proton channel of a V-ATPase7.
Doubts and applications
Morelli and colleagues (2019) reviewed work on proton movement in membranes. They noted a paper describing proton diodes, transistors, memories and transducers that use the Grotthuss mechanism3. For complex IV, they named a proton entrance half channel. They said it is hypothesized that another 4 H+, for a total of 8, enter through it4. They judged it unlikely that protons bound to water as particles are equivalent to protons moving as a charge by the Grotthuss mechanism4. Spikes and colleagues, by contrast, took their structures as evidence for the mechanism5.
The law that light must be absorbed in order to produce an effect was first clearly enunciated by Grotthus (1819, p. 101)
Bayliss, W. M., 1915 · Principles of General Physiology · open at passage 2355We still do not know how complex I works, especially how electron transfer is coupled to proton translocation.
Kühlbrandt W, 2015 · Structure and function of mitochondrial membrane protein complexes · open at passage 32presents devices such as proton diodes, transistors, memories and transducers, semiconductor electronic devices that use the Grotthuss mechanism
Morelli AM, Ravera S, Calzia D, Panfoli I, 2019 · An update of the chemiosmotic theory as suggested by possible proton currents… · open at passage 23It seems unlikely that there exists equivalence between protons that exist as particles and link to water molecules and protons that should move as a charge, according to the Grotthuss mechanism.
Morelli AM, Ravera S, Calzia D, Panfoli I, 2019 · An update of the chemiosmotic theory as suggested by possible proton currents… · open at passage 31provide evidence of the operation of a Grotthus mechanism of proton translocation (40) in the inlet half channel of the transmembrane proton pathway through the membrane domain.
Spikes TE, Montgomery MG, Walker JE, 2020 · Structure of the dimeric ATP synthase from bovine mitochondria · open at passage 4The electron current through the respiratory chain drives proton translocation across the membrane, from the inside mitochondrial matrix (negative side, n) to the outside intermembrane space (positive side, p)
Brzezinski P, Moe A, Ädelroth P, 2021 · Structure and Mechanism of Respiratory III-IV Supercomplexes in Bioenergetic… · open at passage 1recent data suggest the presence of an ordered water channel in ATP synthase, which via a Grotthus mechanism, could channel protons.
Nunn AVW, Guy GW, Bell JD, 2022 · Bioelectric Fields at the Beginnings of Life · open at passage 25