What is the Difference Between Transaldolase and Transketolase?

Transaldolase and transketolase are two enzymes involved in the non-oxidative phase of the pentose phosphate pathway, a metabolic pathway that takes place parallel to glycolysis and generates NADPH and ribose-5-phosphate for nucleotide synthesis. The main differences between these two enzymes are:

1. Carbon transfer: Transketolase transfers a two-carbon unit from a ketose donor to an aldose acceptor, while transaldolase transfers a three-carbon unit between two sugar molecules.
2. Reaction mechanism: The transaldolase reaction begins with aldol cleavage, which is the cleavage of a bond in a β-hydroxy ketone or aldehyde (an aldol). Transketolase, on the other hand, simply cleaves off the ketone group from the substrate and does not perform an aldol cleavage.
3. Cofactors: Transketolase requires thiamine pyrophosphate (TPP) as a cofactor, while transaldolase does not.
4. Substrates: Transaldolase catalyzes the conversion of sedoheptulose 7-phosphate and glyceraldehydes 3-phosphate, whereas transketolase catalyzes the conversion of xylulose 5-phosphate and ribose 5-phosphate.

In summary, transaldolase and transketolase are both involved in the pentose phosphate pathway, but they differ in their carbon transfer reactions, reaction mechanisms, cofactors, and substrates.

Comparative Table: Transaldolase vs Transketolase

Transaldolase and transketolase are two enzymes that participate in the pentose phosphate pathway, a metabolic pathway that generates NADPH and ribose-5-phosphate for nucleotide synthesis. Here is a comparison table highlighting the differences between these two enzymes:

In summary, transaldolase transfers a three-carbon unit, while transketolase transfers a two-carbon unit. Additionally, transaldolase is a pyridoxal phosphate (PLP)-dependent enzyme, and transketolase is a thiamine pyrophosphate (vitamin B1)-dependent enzyme.