6-phosphogluconate dehydrogenase

Definition

6-phosphogluconate dehydrogenase is an enzyme that catalyzes the oxidative decarboxylation of 6-phosphogluconate to ribulose-5-phosphate, playing a crucial role in the pentose phosphate pathway. This enzyme is essential for producing NADPH and ribose-5-phosphate, which are vital for biosynthetic reactions and nucleotide synthesis, respectively.

5 Must Know Facts For Your Next Test

1. 6-phosphogluconate dehydrogenase is an allosteric enzyme that can be regulated by the concentration of NADP+ and NADPH, allowing the cell to adapt to metabolic needs.
2. This enzyme operates in the oxidative phase of the pentose phosphate pathway, which is crucial for generating reducing equivalents in the form of NADPH.
3. The reaction catalyzed by 6-phosphogluconate dehydrogenase is the second step of the oxidative phase, following the conversion of glucose-6-phosphate to 6-phosphogluconolactone.
4. Deficiency in 6-phosphogluconate dehydrogenase can lead to various metabolic disorders, affecting cellular redox status and nucleotide synthesis.
5. The activity of this enzyme can influence overall cellular metabolism by affecting both the availability of NADPH for biosynthetic processes and the levels of ribose-5-phosphate for nucleotide synthesis.

Review Questions

• How does 6-phosphogluconate dehydrogenase contribute to the overall function of the pentose phosphate pathway?
  • 6-phosphogluconate dehydrogenase plays a pivotal role in the pentose phosphate pathway by catalyzing the conversion of 6-phosphogluconate to ribulose-5-phosphate while generating NADPH. This reaction is essential because it not only contributes to the production of NADPH, which is crucial for reductive biosynthesis, but also provides ribulose-5-phosphate, a precursor for nucleotide synthesis. Thus, this enzyme helps maintain the balance between oxidation and reduction in cellular metabolism.
• Discuss how the regulation of 6-phosphogluconate dehydrogenase affects cellular metabolism.
  • The regulation of 6-phosphogluconate dehydrogenase is vital for cellular metabolism as it responds to changes in the concentrations of NADP+ and NADPH. High levels of NADPH can inhibit the enzyme, reducing its activity when sufficient reducing power is present. Conversely, when NADP+ levels are high, indicating a need for more reducing equivalents, the enzyme's activity increases. This regulation allows cells to adapt their metabolic processes based on current needs, ensuring efficient use of resources.
• Evaluate the potential consequences of a deficiency in 6-phosphogluconate dehydrogenase on human health.
  • A deficiency in 6-phosphogluconate dehydrogenase can lead to significant metabolic issues, particularly affecting redox balance within cells. Without sufficient NADPH production, cells may struggle with anabolic processes such as fatty acid synthesis and maintaining antioxidant defenses. This deficiency can also impair nucleotide synthesis due to reduced ribose-5-phosphate availability. The resulting metabolic disturbances can manifest in conditions like hemolytic anemia or other oxidative stress-related disorders, highlighting the enzyme's critical role in maintaining cellular health.

Related terms

Pentose Phosphate Pathway: A metabolic pathway that generates NADPH and ribose-5-phosphate from glucose-6-phosphate, providing reducing power for anabolic reactions and precursors for nucleotide synthesis.

NADPH: Nicotinamide adenine dinucleotide phosphate, a coenzyme that serves as a reducing agent in anabolic reactions, essential for fatty acid synthesis and maintaining cellular redox balance.

Ribulose-5-phosphate: A sugar phosphate molecule produced during the pentose phosphate pathway that serves as a substrate for the synthesis of ribose-5-phosphate and other sugars.