Pentose Phosphate Pathway Flashcards
Where does the PPP occur?
In the cytosol of cells
What is the PPP?
An alternate pathway for metabolism of glucose (does not produce energy)
What is the main purpose of the PPP?
Provides NADPH+H and provides pentoses for DNA/RNA
Where is the pentose phosphate pathway active?
Liver, lactation mammary glands, adipose tissue (provides NADPH for fatty acid biosynthesis). Adrenal cortex, testis, and ovaries (provides NADPH for synthesis of steroid hormones). Erythrocytes (NADPH for the reduction of glutathione) and white blood cells and macrophages (provides NADPH for phagocytosis).
Oxidative Phase of PPP
Irreversible reactions. Forms NADPH and pentose phosphate. Enzymes ate dehydrogenases (G6PD)/
Nonoxidative Phase of PPP
Reversible reactions that occur where pentoses are not required by cells. Involves the inter conversion of sugars resulting in the formation of glycolytic intermediates. Uses transketolase (TPP) and transaldolase.
What is the coenzyme for transketolase?
TPP (thiamine pyrophosphate)
Uses of NADPH
Reduction and detoxification of hydrogen peroxide and phagocytosis in WBCs.
Phagocytosis by WBCs
During phagocytosis, superoxide radicals are generated using NADPH oxidase (requires NADPH).
What does a deficiency of NADPH oxidase cause?
Chronic granulomatous disease, which is characterized by severe and persistent infections which result in an increased production of oxidants.
Three signs of hemolysis
Jaundice (increased serum bilirubin), lower hemoglobin value urine is reddish brown and positive for hemoglobin
G6PD deficiency
Most common enzyme abnormality (X-linked recessive). Impaired ability to form NADPH, which reduces the glutathione pool. Which results in a decrease of free radicals and peroxides, resulting in hemolysis.
