Fermentation Flashcards
Substrates, Enzyme, and Products in Lactic Acid Fermentation
Pyruvate + NADH + H+, lactate dehydrogenase (LDH), L-Lactate + NAD+
How many ATP does lactic acid fermentation create?
2 ATP
%efficiency of lactic acid fermentation?
about 31% as the rest of the energy is released as heat
Can you consider it efficient?
No, but it compensates for its rate.
What happens when there is an excess of lactic acid?
Excess lactic acid can lead to fatigue, and in some cases, even death
What product can undergo what metabolic pathway?
NAD+ can undergo glycolysis again. Lactate, when delivered to the liver can undergo gluconeogenesis.
Where does lactic acid fermentation take place?
muscle cells and red blood cells
what are the two applications of lactic acid fermentation in muscle cells?
slow twitch (in red meat birds that can also undergo oxidative phosphorylation) and fast twitch (in white meat birds for sudden demands of energy)
How does LDH catalyze fermentation?
Hydride transfer from NADH to pyruvate forming the products.
Substrates, Enzyme, and Products in Ethanol Fermentation
Pyruvate to acetaldehyde via pyruvate decarboxylase with TPP and Mg2+
Acetaldehyde to ethanol via alcohol dehydrogenase
%efficiency of EtOH fermentation? Comment its efficiency.
About 26% which is not very efficient but can compensate for its rate.
How does/do the enzyme/s catalyze the reaction/s in ethanol fermentation?
decarboxylation of pyruvate via pyruvate decarboxylase is done to release CO2. Acidic proton of thiazolium ring from TPP is mainly involved in the reaction.
hydride transfer from NADH to NAD+ reduces acetaldehyde to ethanol
Why is TPP present?
Acts as an electron sink to prevent formation of unstable electron-rich carbanion intermediate
If the enzyme liver alcohol dehydrogenase is introduced instead of alcohol dehydrogenase, what would happen?
Will favor the reverse reaction. Ethanol will be oxidized to acetaldehyde.
