Rules to Explain the Diversity

The direct energetic comparison of different cycles is sometimes questionable, as the reducing power of various electron donors is not the same. For example, the reduction potential of reduced ferredoxin is stronger than that of the reduced pyridine nucleotides. In growing cells, ferredoxin is often reduced by a hydroge- 

1 +4 3-hydroxypropionate/malyl-CoA cycle 1 +3 3-hydroxypropionate/4-hydroxybutyrate cycle 2+5 reductive citric acid cycle 2+4 dicarboxylate/4-hydroxybutyrate cycle 

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