Pentose_Phosphate_Pathway_Presentation.pptx
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This presentation provides a detailed overview of the Pentose Phosphate Pathway (PPP), also known as the Hexose Monophosphate Shunt. It covers the two distinct phases of the pathway—oxidative and non-oxidative—highlighting key enzymes, intermediates, and end products. The role of PPP in generating NADPH and ribose-5-phosphate, along with its significance in biosynthetic processes and protection against oxidative stress, is explained. Clinical relevance, particularly in relation to glucose-6-phosphate dehydrogenase (G6PD) deficiency, is also discussed. This resource is ideal for students of biochemistry, medicine, and allied health sciences.
Pentose_Phosphate_Pathway_Presentation.pptx
- 1. PENTOSE PHOSPHATE PATHWAY (PPP) Hexose Monophosphate (HMP) Shunt BIOCHEMISTRY LECTURE BY: SHIVANGI
- 2. INTRODUCTION The Pentose Phosphate Pathway is an alternative pathway of glucose oxidation. It does not produce ATP directly. It serves two major functions: - Production of NADPH - Synthesis of Ribose-5-phosphate for nucleic acid synthesis
- 3. LOCATION Cellular Location: Cytoplasm Active in: Liver, adipose tissue, adrenal cortex, erythrocytes High activity in cells performing fatty acid and steroid synthesis
- 4. FUNCTIONS OF PPP 1. Generation of NADPH – for reductive biosynthesis (fatty acids, cholesterol) and protection against oxidative stress. 2. Production of Ribose-5-phosphate – essential for nucleotide and nucleic acid synthesis. 3. Interconversion of sugars – link to glycolysis via intermediates.
- 5. PHASES OF PPP Two Phases: Oxidative Phase – irreversible Non- Oxidative Phase – reversible
- 7. OXIDATIVE PHASE (REACTIONS) 1. Glucose-6-phosphate 6- → Phosphoglucono-δ-lactone - Enzyme: Glucose-6-phosphate dehydrogenase (G6PD) - Produces NADPH 2. 6-Phosphoglucono-δ-lactone 6- → Phosphogluconate - Enzyme: Lactonase 3. 6-Phosphogluconate Ribulose- → 5-phosphate - Enzyme: 6-Phosphogluconate dehydrogenase - Produces NADPH + CO₂
- 8. SUMMARY OF OXIDATIVE PHASE • Products per glucose: - 2 NADPH - 1 Ribulose-5-phosphate - 1 CO₂
- 9. NON-OXIDATIVE PHASE (REACTIONS) 1. Ribulose-5-phosphate Ribose- → 5-phosphate - For nucleotide synthesis 2. Interconversion reactions: - Transketolase & Transaldolase enzymes - Convert 3 C5 sugars C3, C6, C7 → sugars - Intermediates: Glyceraldehyde- 3-phosphate, Fructose-6-phosphate
- 10. Source of image: MEDSCHOOL Coach
- 11. KEY ENZYMES • Glucose-6-phosphate dehydrogenase (G6PD) - Rate-limiting enzyme - Inhibited by high NADPH • Transketolase (requires TPP) • Transaldolase
- 12. REGULATION OF PPP Controlled by NADP⁺ levels High NADP⁺ activates G6PD → Low NADP⁺ or high NADPH → inhibits G6PD
- 13. CLINICAL CORRELATION G6PD Deficiency: • X-linked recessive disorder • Decreased NADPH impaired protection from → oxidative stress • Leads to hemolytic anemia under oxidative stress (fava beans, drugs, infections)
- 14. IMPORTANCE OF NADPH Fatty acid synthesis Cholesterol and steroid hormone synthesis Detoxification (cytochrome P450 system) Maintaining reduced glutathione in RBCs (antioxidant defense)
- 15. SUMMARY • PPP is vital for biosynthesis and cellular protection • Oxidative phase generates NADPH → • Non-oxidative phase provides sugar phosphates for → other pathways • Regulated by NADP⁺/NADPH ratio
- 16. REFERENCES Lehninger Principles of Biochemistry Harper’s Illustrated Biochemistry Lippincott’s Biochemistry Review