ISSN:
1432-072X
Keywords:
Key words ATP synthase
;
Decarboxylation
;
Electrogenic substrate/product antiporter
;
Sodium ion
;
pump
;
Malo-lactic fermentation
;
Oxalate
;
Malonate
;
Succinate
;
Glutarate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Decarboxylation of dicarboxylic acids (oxalate, malonate, succinate, glutarate, and malate) can serve as the sole energy source for the growth of fermenting bacteria. Since the free energy change of a decarboxylation reaction is small (around –20 kJ per mol) and equivalent to only approximately one-third of the energy required for ATP synthesis from ADP and phosphate under physiological conditions, the decarboxylation energy cannot be conserved by substrate-level phosphorylation. It is either converted (in malonate, succinate, and glutarate fermentation) by membrane-bound primary decarboxylase sodium ion pumps into an electrochemical gradient of sodium ions across the membrane; or, alternatively, an electrochemical proton gradient can be established by the combined action of a soluble decarboxylase with a dicarboxylate/monocarboxylate antiporter (in oxalate and malate fermentation). The thus generated electrochemical Na+ or H+ gradients are then exploited for ATP synthesis by Na+- or H+-coupled F1F0 ATP synthases. This new type of energy conservation has been termed decarboxylation phosphorylation and is responsible entirely for ATP synthesis in several anaerobic bacteria.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050616
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