PPP, Glucuronate Pathway & Lactose Synthesis

Detailed description of Pentose Phosphate Pathway, Glucuronate Pathway & Lactose synthesis

1. METABOLISM - I Pentose Phosphate Pathway Glucuronate Pathway Lactose Synthesis Submitted by : Diwakar Sharma M.Sc Biochemistry, Semester – II, First Year

2. Pentose Phosphate Pathway also called the phosphogluconate pathway or the hexose monophosphate pathway

3. Pentose Phosphate Pathway OVERVIEW:- NADPH production Glutathione reduction (E), fatty acid/cholesterol synthesis (L) Glycolytic intermediates Fructose-6-phosphate, glyceraldehyde-3-phosphate Ribose-5-phosphate & Xylulose , Ribulose ( Pentoses ) Nucleotide synthesis (nucleated cells)

4. Pentose Phosphate Pathway Glycolysis to PPP

5. Pentose Phosphate Pathway Oxidative Phase Source: Lehninger

6. Pentose Phosphate Pathway Non-oxidative Phase Source: Lehninger

7. Pentose Phosphate Pathway Glucose 6-Phosphate Is Partitioned between Glycolysis and the PPP Source: Lehninger

8. Glucuronate Pathway Also called uronic acid pathway

9. Glucuronate Pathway An alternative pathway for the oxidation of glucose that does not provide a means of producing ATP, but is utilized for the generation of the activated form of glucuronate , UDP- glucuronate which is mainly used for detoxification of foreign chemicals and for the synthesis of Mucopolysaccharides . This pathway also produces Ascorbic Acid in certain animals. The unutilized Glucuronate produced in this pathway is converted to Xylulose 5-phosphate which is further metabolized through PPP.

10. to HMP Shunt or PPP 1. Formation of UDP glucose Steps: 2. Formation of Glucuronic acid

11. Glucuronate Pathway In animals synthesizing this vitamin C In humans PPP...

12. Lactose Synthesis Also called milk sugar.

13. Lactose Synthesis Lactose, the disaccharide of milk, consists of galactose joined to glucose by a β -1,4-glycosidic linkage. Lactose is hydrolyzed to these monosaccharides by lactase in human beings and by β - galactosidase in bacteria.

14. Gal-1-phosphate Uridylyl-transferase 1 UDP Gal translocator GLUT-1 Galactosyl - transferase Lactose Synthase UMP translocator

15. Lactose Synthesis Glucose is first converted to UDP- galactose via the enzyme galactose-1-phosphate uridylyltransferase . UDP- galactose is then transported into the Golgi by the UDP galactose translocator , an antiporter which uses facilitated transport to move UDP galactose into the Golgi and exports UMP. Once inside the Golgi, the UDP galactose and glucose (which moves into the golgi via the GLUT-1 transporter) become substrates for the lactose synthase enzyme complex, comprised of the enzymatic subunit, galactosyltransferase with its regulatory subunit, Alpha- lactalbumin . Lactose synthase creates lactose through bonding galactose from UDP to glucose through a glycosidic bond. Although GT is found in many tissues in the body, Alpha- lactalbumin is only found on the inner surface of the Golgi in the mammary glands, limiting lactose production to the mammaries .