Biochemistry and Molecular Biology - Belyasova N.A. 2002

Metabolism. Energy-Yielding Processes
Fermentation
Substrate-Level Phosphorylation Reactions

The processes of the most common Types of Fermentation—alcoholic and lactic acid—outlined above reveal A wide variety of pathways and Mechanisms for the formation of end products.

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Fig. 10.3. Substrate-level phosphorylation reactions

As previously mentioned, there are at least four other Major Types of fermentation. It is important to note that the nature, spectrum, and relative amounts of the End products of any given fermentation type depend both on the Organism itself (its species) and on the incubation conditions (or the intracellular environment).

Thus, one can identify a multitude of diverse Chemical Reactions associated either with fermentation proper or with preparatory stages (Catabolic pathways of carbohydrate degradation). However, out of this multitude, only a handful of reactions provide energy storage at the substrate-level phosphorylation stage (Fig. 10.3). It should be emphasized that the first two reactions shown in Fig. 10.3 occur during Glycolysis, whereas reactions 3 through 5 pertain specifically to fermentation. The synthesis of ATP during The formation of acetate, acetoacetate, and butyrate (butyric acid) takes place in Butyric Acid and acetone-butanol fermentations. The final, 6th reaction of substrate-level phosphorylation shown in Fig. 10.3 occurs in The Tricarboxylic Acid Cycle.