Dear all:
I am trying to get a clue on the carbon flow and energy conservation in anaerobes, and the role that acetyl-CoA plays in the overall process
Acetyl-CoA has been well-recognized as an important molecule in metabolism, especially for energy generation through TCA cycle under aerobic conditions; but how about its role in the anaerobic microorganisms? its importance is more lying in the synthesis of carbon skeletons for anaerobes or is also important in energy supply?
In my current understanding, the generation of butyrate, propionate, ethanol from acetyl-CoA is more a process to regenerate NAD+ for the cycling of glycosis, rather than an energy generation process, so what would be the other energy conservation routes the anaerobes may apply?
Thanks in advance!
Yubo
Respiration/Electron transfer chains? All the dissimilatory redox cycles are focused on energy production: sulfate reduction, Fe(III)-respiration,...
Xabier, thanks a lot for your information!
i once was told that all the redox reactions should be energy generating, but i am not sure whether the reducing power is originated mainly in the glycolysis process?
The energy generation through hydrolysis of chemical bonds, e.g. thioester-bond (S-CoA) may be more independent of the redox reactions, also it seems that the methyl tranfer process faciliated by mtr enzyme in methanogenesis process is energy generating; apart these two, any other redox-indepedent energy-generating processes in anaerobic process?
the acetyl-CoA is not that involved in the energy generating process in anaerobes? its role is more related to the biosythesis?
When I said redox cycles, I was referring to the environmental redox cycles, e.g. Fe, N, S,... where microbes usually have a role by using those elements in their diverse redox states as electron acceptor or donors. i.e. respiration.
Respiration usually leads to the generation of reducing power by the electron transfer chain. It also pumps H+ that consequently generate a gradient. This gradient, leads to the production of ATP by the proton motive force (ATPases).
Yubo, I hope the text below answers your questions:
...Following glycolysis, pyruvate may be converted into acetyl coenzyme A (acetyl CoA) and continue in the aerobic respiration pathway through the citric acid cycle. Alternatively it may be converted to lactate or used to synthesise fatty acid or ketone bodies. The former occurs if oxygen levels are low, producing lactate for use in anaerobic respiration. The latter occurs when excess ATP is present in the cell, and the rate of the citric acid cycle slows down. As less acetyl CoA is used in the cycle it accumulates and the excess it converted to ketone bodies and fatty acids for eventual storage....
Adopted from: http://www.fastbleep.com/biology-notes/40/116/752
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