Lecture Notes on HMP Shunt

Introduction

• HMP Shunt is known as Hexose Monophosphate Shunt or Pentose Phosphate Pathway.
• It is an alternative pathway for glucose oxidation.
• Primarily useful for the production of NADPH and Ribose-5-Phosphate.

Location

• HMP Shunt is mainly active in the adrenal glands, testes, ovaries, lactating breasts, and erythrocytes.

Enzyme

• Glucose-6-phosphate dehydrogenase is the rate-limiting enzyme of this pathway.

Uses of NADPH

• NADPH is essential for fatty acid, steroid, and cholesterol biosynthesis.
• Necessary for antioxidant function.

G6PD Deficiency

• When there is a deficiency of glucose-6-phosphate dehydrogenase, issues may arise when oxidant drugs are administered.

Pathway Stages

1. Oxidative Phase:
   • Production of NADPH.
   • Involvement of 6-phosphogluconate dehydrogenase.
2. Non-Oxidative Phase:
   • Production of Ribose-5-Phosphate.
   • Actions of transketolase and transaldolase.

Importance

• 30% of glucose utilization occurs through the HMP Shunt.
• Necessary for DNA and RNA synthesis.
• Low NADPH levels affect RBC membranes.

Conclusion

• The HMP Shunt passes through two phases: oxidative and non-oxidative.
• Pentose sugars are precursors for nucleotide synthesis.