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Evolution of bioenergetics
All processes in living cells are energy-dependent. Apart from the comparatively inefficient
fermentation pathway, this energy is invariably provided by the "Mitchellian" chemiosmotic
mechanism, that is, by the conversion of a proton-motive-force (pmf) across a "bioenergetic
membrane" into ATP-synthesis via the enzyme ATPase.
In the vast majority of cases, the pmf is produced by the coupling of electron transport
to the vectorial translocation of positively charged ions (generally protons, H+) across
the bioenergetic membrane (Figure 1). In a few archaeal species, the bioenergetic membrane
potential is alternatively built up directly by light-driven ion-translocation performed by
the enzyme Bacteriorhodopsin.
Life thus mainly draws its energy from collapsing electrochemical disequilibria of redox-active
substrates. Such disequilibria may be provided by geo-/biochemical processes in the environment
or induced by life itself via photochemical mechanisms (i.e. chlorophyll-based photosynthesis).
In eukaryotes, the corresponding electron transfer chains are almost invariably aerobic respiration
(in mitochondria) or oxygenic photosynthesis (in chloroplasts). Prokaryotes, by contrast, feature
a bewildering diversity of bioenergetic electron transfer chains and are probably able to use all
bio-available redox compounds as substrates for energy conversion, either as reductants or oxidants.
Figure 2 represents a few selected examples of this -probably far from exhaustively known- diversity
of prokaryotic electron transfer chains.
(click on enzymes or quinones to get more detailed information)
BIP09 studies selected prokaryotic energy conserving chains with the aim of contributing to a
comprehensive picture of the diversity of these chains but also of elaborating common features
and conserved principles. The ultimate goal of this approach is to contribute to the elucidation
of the origin(s) and evolutionary pathways of biological energy conversion
To obtain more information about segments of individual chains which are (or have in the past been)
addressed by our group, please click on the corresponding item in Figure 2.
For a description of our results concerning conserved protein subunits in bioenergetic
enzymes, please visit our page "The redox-enzyme construction kit" .
Since January 2018 we have initiated a new project addressing potential evolutionary links between the catalytic sites in metalloenzymes and specific minerals present in hydrothermal settings. Results obtained with respect to this topic are dealt with in our "Minerals-first" pages
The general pertinence of the evolution of bioenergetics to how it all began is discussed in our pages Energy and the Emergence of Life"
One of the most fundamental principles of biological energy conversion is the interlacing of 1- and 2-electron transfer events. Prominent actors in the schemes of multi-electron gates are quinones and flavins. The electrochemistry of these 2-electron compounds is versatile and crucially underlies many redox reactions at the very heart of the bioenergetic process. We have tried and summarised the basic mathematical formalism describing 2-electron redox transitions on a dedicated 2-electron webpage
Last update: September 21 2020
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