Hmp shunt pathway

HMP shunt pathway is a shunt pathway from glycolytic pathway. starting form glucose 6 pasphat by the action of an enzymes known as g6pd. by this pathway an important reducing substance named NADPH2 is produce which result in reducing other substances for its synthesis.

1. Pentose Phosphate Pathway Muhammad asif Zeb Lecturer- Hematology IPMS KMU

2. The pentose phosphate pathway (also called the hexose monophosphate pathway , or 6-phosphogluconate pathway) occurs in the cytosol of the cell. No ATP is directly consumed or produced in the cycle. Carbon 1 of glucose 6-phosphate is released as CO2, and two NADPH are produced for each glucose 6-phosphate molecule. Introduction

3. Reaction of the Pathway

4. HMP pathway consists of two reactions that lead to the formation of ribulose 5-phosphate, CO2, and two molecules of NADPH for each molecule of glucose 6-phosphate oxidized . this pathway is particularly important for fatty acids in liver , lactating mammary glands, Adipose, For steroid hormones in In the testes, ovaries, placenta and adrenal cortex In erythrocytes to keep glutathione in Reduced form. IRREVERSIBLE OXIDATIVE REACTIONS

5. G6PD catalyzes an irreversible oxidation of glucose 6-phosphate to 6-phosphogluconolactone The pentose phosphate pathway is regulated primarily at the G6PD reaction . NADPH is a potent competitive inhibitor of the enzyme Insulin upregulates expression of the gene for G6PD , A. Dehydrogenation of glucose 6-phosphate

6. 6-PG is hydrolyzed by 6-pg hydrolase. The reaction is irreversible The oxidative decarboxylation of the product, 6-phosphogluconate is catalyzed by 6-phosphogluconate dehydrogenase . This irreversible reaction produces a pentose sugar–phosphate ( ribulose 5-phosphate ), CO2, and a second molecule of NADPH B. Formation of ribulose 5-phosphate

7. The nonoxidative reactions of the pentose phosphate pathway occur in all cell types synthesizing nucleotides and nucleic acids. These reversible reactions permit ribulose 5-phosphate to be converted either to ribose 5-phosphate (needed for nucleotide synthesis) or to intermediates of glycolysis—fructose 6-phosphate and glyceraldehyde 3-phosphate. III. REVERSIBLE NONOXIDATIVE REACTIONS

8. Reduction of hydrogen peroxide Phagocytosis by white blood cells Production of Nitric oxide Uses of NADPH

9. Hydrogen peroxide is one of a family of reactive oxygen species (ROS ) that are formed from the partial reduction of molecular Oxygen The highly reactive oxygen intermediates can cause serious chemical damage to DNA , proteins, and unsaturated lipids, and can lead to cell death Reduction of hydrogen peroxide

10. Phagocytosis by white blood cells