A. Introduction and Significance B. Glycolytic Sowing C. Glycolytic Reeping D. Net Glycolysis E. Pyruvate s Fate

1. http://www.er.doe.gov/feature_articles_2001/June/Decades/92.html Many mysteries of the human brain have been unraveled by positron emission tomography (PET), an imaging tool used worldwide to diagnose cancer and heart disease and perform scientific studies. The development and usefulness of PET—which offers a millionfold greater sensitivity than other techniques for studying regional metabolism and neuroreceptor activity in the brain and other tissues—rests on a number of advances made with Office of Science support. Much of the credit is due to Alfred P. Wolf, a chemist at Brookhaven National Laboratory known as the father of organic radiochemistry, a field that links medicine and chemistry. In 1976, Wolf and colleagues developed and used a radiotracer called 18-fluorodeoxyglucose (a combination of the short-lived radioactive element fluorine-18 and a sugar, glucose) to generate the first functional map of the human brain at work. When a radiotracer is injected into the body, its signal is picked up by PET equipment. Glucose is virtually the only energy source for the brain, so images of the location of 18-FDG provide a signature or map of brain function. This development enabled scientists to see, for the first time, regions of the human brain "lit up" in response to stimuli such as looking, listening, and remembering.http://www.er.doe.gov/feature_articles_2001/June/Decades/92.html Many mysteries of the human brain have been unraveled by positron emission tomography (PET), an imaging tool used worldwide to diagnose cancer and heart disease and perform scientific studies. The development and usefulness of PET—which offers a millionfold greater sensitivity than other techniques for studying regional metabolism and neuroreceptor activity in the brain and other tissues—rests on a number of advances made with Office of Science support. Much of the credit is due to Alfred P. Wolf, a chemist at Brookhaven National Laboratory known as the father of organic radiochemistry, a field that links medicine and chemistry. In 1976, Wolf and colleagues developed and used a radiotracer called 18-fluorodeoxyglucose (a combination of the short-lived radioactive element fluorine-18 and a sugar, glucose) to generate the first functional map of the human brain at work. When a radiotracer is injected into the body, its signal is picked up by PET equipment. Glucose is virtually the only energy source for the brain, so images of the location of 18-FDG provide a signature or map of brain function. This development enabled scientists to see, for the first time, regions of the human brain "lit up" in response to stimuli such as looking, listening, and remembering.

2. Lactose intolerance: Lactose + H2O ? D-galactose + D-glucose – something wrong with lactase In small intestine, lactose is not properly absorbed In large intestine, lactose is converted into toxic products ? abdominal cramps/diarrhea ?[lactose] leads to ? osmolarity and ? water retention in the intestine There is generally a disappearance of lactase from the intestinal walls after childhood, which makes sense since the child would have stopped breast feeding! Cancer cells: Cancer cells have limited capillary networks at their inception and therefore limited access to O2 Therefore, glycolysis and the anaerobic conversion of pyruvate ? lactate is used to regenerate NAD+ There are a smaller number of mitochondria in tumour cells – therefore, less ATP is made during OxPhos Therefore, the cells need more energy from glycolysis, which is why some tumour cells overproduce glycolytic enzymes Hypoxia-induced transcription factor (HIF-1) acts at the level of mRNA synthesis to stimulate the production of 8 glycolytic enzymes … Therefore, cancer cells can survive by glycolysis until the capillary supply catches up with the tumour growth!!!Lactose intolerance: Lactose + H2O ? D-galactose + D-glucose – something wrong with lactase In small intestine, lactose is not properly absorbed In large intestine, lactose is converted into toxic products ? abdominal cramps/diarrhea ?[lactose] leads to ? osmolarity and ? water retention in the intestine There is generally a disappearance of lactase from the intestinal walls after childhood, which makes sense since the child would have stopped breast feeding! Cancer cells: Cancer cells have limited capillary networks at their inception and therefore limited access to O2 Therefore, glycolysis and the anaerobic conversion of pyruvate ? lactate is used to regenerate NAD+ There are a smaller number of mitochondria in tumour cells – therefore, less ATP is made during OxPhos Therefore, the cells need more energy from glycolysis, which is why some tumour cells overproduce glycolytic enzymes Hypoxia-induced transcription factor (HIF-1) acts at the level of mRNA synthesis to stimulate the production of 8 glycolytic enzymes … Therefore, cancer cells can survive by glycolysis until the capillary supply catches up with the tumour growth!!!

3. BOX 14-2 FIGURE 3 Detection of cancerous tissue by positron emission tomography (PET). The adult male patient had undergone surgical removal of a primary skin cancer (malignant melanoma). The image on the left, obtained by whole-body computed tomography (CT scan), shows the location of the soft tissues and bones. The central panel is a PET scan after the patient had ingested 18F-labeled 2-fluoro-2-deoxyglucose (FdG). Dark spots indicate regions of high glucose utilization. As expected, the brain and bladder are heavily labeled?the brain because it uses most of the glucose consumed in the body, and the bladder because the 18Flabeled 6-phospho-FdG is excreted in the urine. When the intensity of the label in the PET scan is translated into false color (the intensity increases from green to yellow to red) and the image is superimposed on the CT scan, the fused image (right) reveals cancer in the bones of the upper spine, in the liver, and in some regions of muscle, all the result of cancer spreading from the primary malignant melanoma.BOX 14-2 FIGURE 3 Detection of cancerous tissue by positron emission tomography (PET). The adult male patient had undergone surgical removal of a primary skin cancer (malignant melanoma). The image on the left, obtained by whole-body computed tomography (CT scan), shows the location of the soft tissues and bones. The central panel is a PET scan after the patient had ingested 18F-labeled 2-fluoro-2-deoxyglucose (FdG). Dark spots indicate regions of high glucose utilization. As expected, the brain and bladder are heavily labeled?the brain because it uses most of the glucose consumed in the body, and the bladder because the 18Flabeled 6-phospho-FdG is excreted in the urine. When the intensity of the label in the PET scan is translated into false color (the intensity increases from green to yellow to red) and the image is superimposed on the CT scan, the fused image (right) reveals cancer in the bones of the upper spine, in the liver, and in some regions of muscle, all the result of cancer spreading from the primary malignant melanoma.

4. Metabolism 320 Starch is a major source of carbohydrates in the diet. Sucrose + H2O ? D-fructose + D-glucose (sucrase) Maltose + H2O ? 2 D-glucose (maltase) Lactose + H2O ? D-galactose + D-glucose (lactase) Dextrin + H2O ? D-fructose + D-glucose (dextrinase) (?1?6) Trehalose + H2O ? 2 D-glucose (trehalase)Starch is a major source of carbohydrates in the diet. Sucrose + H2O ? D-fructose + D-glucose (sucrase) Maltose + H2O ? 2 D-glucose (maltase) Lactose + H2O ? D-galactose + D-glucose (lactase) Dextrin + H2O ? D-fructose + D-glucose (dextrinase) (?1?6) Trehalose + H2O ? 2 D-glucose (trehalase)

5. Glucose in central in metabolism of plants/animals and many microbes.Glucose in central in metabolism of plants/animals and many microbes.

7. This all happens in the cytosol – glycolytic enzymes are soluble. Add a phosphoryl group into glucose – kinase Isomerize glucose-6-P – isomerase Add a phosphoryl group to fructose-6-P – kinase Break and ALMOST symmetrical molecule in two – each half is primed with a phosphoryl group – aldolase Convert DHAP to Glyc-3-P - isomeraseThis all happens in the cytosol – glycolytic enzymes are soluble. Add a phosphoryl group into glucose – kinase Isomerize glucose-6-P – isomerase Add a phosphoryl group to fructose-6-P – kinase Break and ALMOST symmetrical molecule in two – each half is primed with a phosphoryl group – aldolase Convert DHAP to Glyc-3-P - isomerase

8. Kinases are a form of transferase – can also phosphorylate D-fructose and D-mannose. Hexose binding causes an induced fit and large conformational change. In this case, Mg2+ is associated with ATP4- ? Mg-ATP2- Phosphorylation of any intermediate restricts it from diffusing across the membrane – keeps it compartmentalized. Kinases are a form of transferase – can also phosphorylate D-fructose and D-mannose. Hexose binding causes an induced fit and large conformational change. In this case, Mg2+ is associated with ATP4- ? Mg-ATP2- Phosphorylation of any intermediate restricts it from diffusing across the membrane – keeps it compartmentalized.

10. Specific for the substrates shown.Specific for the substrates shown.

11. The phosphohexose isomerase reaction. The ring opening and closing reactions (steps 1 and 4) are catalyzed by an active-site His residue, by mechanisms omitted here for simplicity. The proton (pink) initially at C-2 is made more easily abstractable by electron withdrawal by the adjacent carbonyl and nearby hydroxyl group. After its transfer from C-2 to the active-site Glu residue (a weak acid), the proton is freely exchanged with the surrounding solution; that is, the proton abstracted from C-2 in step 2 is not necessarily the same one that is added to C-1 in step 3.The phosphohexose isomerase reaction. The ring opening and closing reactions (steps 1 and 4) are catalyzed by an active-site His residue, by mechanisms omitted here for simplicity. The proton (pink) initially at C-2 is made more easily abstractable by electron withdrawal by the adjacent carbonyl and nearby hydroxyl group. After its transfer from C-2 to the active-site Glu residue (a weak acid), the proton is freely exchanged with the surrounding solution; that is, the proton abstracted from C-2 in step 2 is not necessarily the same one that is added to C-1 in step 3.

12. PFK1: major regulatory enzyme (very complex) – distinguish from PFK-2 (fructose-2,6-bisphosphate) If ATP is low in the cell, this activity of this enzyme is increased. PFK1: major regulatory enzyme (very complex) – distinguish from PFK-2 (fructose-2,6-bisphosphate) If ATP is low in the cell, this activity of this enzyme is increased.

18. Glyceraldehyde-3-phosphate dehydrogenase: the enzyme transfers a hydride ion from the aldehyde of G-3-P to the nicotinamide ring of NAD+ and the other hydrogen atom is released to solution as H+. Glyceraldehyde-3-phosphate dehydrogenase: the enzyme transfers a hydride ion from the aldehyde of G-3-P to the nicotinamide ring of NAD+ and the other hydrogen atom is released to solution as H+.

22. Mg2+ is essentialMg2+ is essential

23. Metabolism 320

26. For what is this enzyme a good candidate? Regulation – essentially this is an irreversible process. For what is this enzyme a good candidate? Regulation – essentially this is an irreversible process.

28. This all happens in the cytosol – glycolytic enzymes are soluble. Add a phosphoryl group into glucose – kinase Isomerize glucose-6-P – isomerase Add a phosphoryl group to fructose-6-P – kinase Break and ALMOST symmetrical molecule in two – each half is primed with a phosphoryl group – aldolase Convert DHAP to Glyc-3-P - isomeraseThis all happens in the cytosol – glycolytic enzymes are soluble. Add a phosphoryl group into glucose – kinase Isomerize glucose-6-P – isomerase Add a phosphoryl group to fructose-6-P – kinase Break and ALMOST symmetrical molecule in two – each half is primed with a phosphoryl group – aldolase Convert DHAP to Glyc-3-P - isomerase

32. Metabolism 320

33. Anaerobic conditions also called hypoxia – low oxygen conditions – NADH can not be reoxidized to NAD+ required for glycolysis to continue – fully engaged muscle. Fermentation – plant tissues, certain invertebrates, protists and microorganisms.Anaerobic conditions also called hypoxia – low oxygen conditions – NADH can not be reoxidized to NAD+ required for glycolysis to continue – fully engaged muscle. Fermentation – plant tissues, certain invertebrates, protists and microorganisms.

34. For this reason, this process is promoted if there is oxygen available to accept electrons from NADH and regenerate NAD+ for glycolysis.For this reason, this process is promoted if there is oxygen available to accept electrons from NADH and regenerate NAD+ for glycolysis.

35. 2 molecules of pyruvate are produced for every glucose molecule, and thereby enough NAD+ is regenerated for glycolysis when 2 molecules of pyruvate are converted to 2 molecules of lactate (2 NADH + 2H+ ? 2 NAD+) Lactate can be reconverted to glucose in the liver, but the build up of lactate during strenuous exercise results in acidification from the ionization of lactate causing pain and limits activity – best-conditioned athletes can only sprint for a minute.2 molecules of pyruvate are produced for every glucose molecule, and thereby enough NAD+ is regenerated for glycolysis when 2 molecules of pyruvate are converted to 2 molecules of lactate (2 NADH + 2H+ ? 2 NAD+) Lactate can be reconverted to glucose in the liver, but the build up of lactate during strenuous exercise results in acidification from the ionization of lactate causing pain and limits activity – best-conditioned athletes can only sprint for a minute.

36. There is no net oxidation or reduction during all forms of fermentation since the C:H ratio remains the same. CO2 causes your bread to rise and offers carbonation to many alcoholic beverages.There is no net oxidation or reduction during all forms of fermentation since the C:H ratio remains the same. CO2 causes your bread to rise and offers carbonation to many alcoholic beverages.

37. Pyridoxal phosphate is the prosthetic group of aminotransferases (see Lehninger Chapter 18) [CO2 makes the bubbles in beer, champagne, & causes dough to rise; human liver contains alcohol dehydrogenase where it oxidizes ethanol] Alcohol has a "loosening up" effect on people, by relaxing the capillary blood vessels under the skin. This produces, first, a feeling of warmth, and then a facial flush, which used to be particularly attractive to Europeans living in cold climates. It also "loosens up" people in another sense: by interfering with bloodflow and chemical balance in the brain, it reduces the activity of certain parts of brain that inhibit behaviour, so that a person becomes less shy, more confident and talkative, and easier to arouse sexually. Alcohol is therefore used as a social lubricant to improve relation building, and quite elaborate rituals are formed involving the consumption of alcohol of various kinds. http://www.merck.com/mrkshared/mmanual/section1/chapter3/3m.jsp Vitamin B6 Deficiency And Dependency “Vitamin B6 comprises a group of closely related compounds: pyridoxine, pyridoxal, and pyridoxamine. They are metabolized and phosphorylated in the body to pyridoxal phosphate, which functions as a coenzyme in many reactions, including decarboxylation and transamination of amino acids, deamination of hydroxyamino acids and cysteine, conversion of tryptophan to niacin, and metabolism of fatty acids. Consequently, the vitamin B6 group is important in blood, CNS, and skin metabolism. Vitamin B6 is important in erythropoiesis because pyridoxal phosphate is needed in the formation of -aminolevulinic acid, the rate-limiting step in heme biosynthesis. Primary deficiency is rare, because most foods contain vitamin B6. Nonetheless, an outbreak of convulsions in infants did follow the inadvertent destruction of vitamin B6 in infant formulas. Secondary deficiency may result from malabsorption, alcoholism, oral contraceptive use, chemical inactivation by drugs (eg, isonicotinic acid hydrazide, cycloserine, hydralazine, penicillamine), excessive loss, and increased metabolic activity. Symptoms and Signs Deficiency: The vitamin B6 antagonist deoxypyridoxine produces seborrheic dermatosis, glossitis, cheilosis, peripheral neuropathy, and lymphopenia. Vitamin B6 deficiency can cause convulsions in infants and anemia in adults (usually normocytic but occasionally microcytic). Dependency: Several recessive or X-linked states affect different vitamin B6 apoenzymes, producing symptoms such as convulsions, mental deficiency, cystathioninuria, sideroblastic (iron overload) anemia, urticaria, asthma, and xanthurenic aciduria. Laboratory Findings and Diagnosis At present, there is no generally accepted test of vitamin B6 status. The whole blood level of pyridoxal phosphate is a better indicator than the plasma level. Erythrocyte glutamic pyruvate and oxaloacetic transaminase activities are decreased in vitamin B6 deficiency, but these changes are not diagnostic because of the wide range of values in healthy persons.” Pyridoxal phosphate is the prosthetic group of aminotransferases (see Lehninger Chapter 18) [CO2 makes the bubbles in beer, champagne, & causes dough to rise; human liver contains alcohol dehydrogenase where it oxidizes ethanol] Alcohol has a "loosening up" effect on people, by relaxing the capillary blood vessels under the skin. This produces, first, a feeling of warmth, and then a facial flush, which used to be particularly attractive to Europeans living in cold climates. It also "loosens up" people in another sense: by interfering with bloodflow and chemical balance in the brain, it reduces the activity of certain parts of brain that inhibit behaviour, so that a person becomes less shy, more confident and talkative, and easier to arouse sexually. Alcohol is therefore used as a social lubricant to improve relation building, and quite elaborate rituals are formed involving the consumption of alcohol of various kinds. http://www.merck.com/mrkshared/mmanual/section1/chapter3/3m.jsp Vitamin B6 Deficiency And Dependency “Vitamin B6 comprises a group of closely related compounds: pyridoxine, pyridoxal, and pyridoxamine. They are metabolized and phosphorylated in the body to pyridoxal phosphate, which functions as a coenzyme in many reactions, including decarboxylation and transamination of amino acids, deamination of hydroxyamino acids and cysteine, conversion of tryptophan to niacin, and metabolism of fatty acids. Consequently, the vitamin B6 group is important in blood, CNS, and skin metabolism. Vitamin B6 is important in erythropoiesis because pyridoxal phosphate is needed in the formation of -aminolevulinic acid, the rate-limiting step in heme biosynthesis. Primary deficiency is rare, because most foods contain vitamin B6. Nonetheless, an outbreak of convulsions in infants did follow the inadvertent destruction of vitamin B6 in infant formulas. Secondary deficiency may result from malabsorption, alcoholism, oral contraceptive use, chemical inactivation by drugs (eg, isonicotinic acid hydrazide, cycloserine, hydralazine, penicillamine), excessive loss, and increased metabolic activity. Symptoms and Signs Deficiency: The vitamin B6 antagonist deoxypyridoxine produces seborrheic dermatosis, glossitis, cheilosis, peripheral neuropathy, and lymphopenia. Vitamin B6 deficiency can cause convulsions in infants and anemia in adults (usually normocytic but occasionally microcytic). Dependency: Several recessive or X-linked states affect different vitamin B6 apoenzymes, producing symptoms such as convulsions, mental deficiency, cystathioninuria, sideroblastic (iron overload) anemia, urticaria, asthma, and xanthurenic aciduria. Laboratory Findings and Diagnosis At present, there is no generally accepted test of vitamin B6 status. The whole blood level of pyridoxal phosphate is a better indicator than the plasma level. Erythrocyte glutamic pyruvate and oxaloacetic transaminase activities are decreased in vitamin B6 deficiency, but these changes are not diagnostic because of the wide range of values in healthy persons.”

38. Mammary glands, adrenal cortex, liver and adipose tissue actively synthesize steroids and fatty acids – therefore PPP is dominant in these tissues. Other tissues such as skeletal muscle mostly lack the PPP.Mammary glands, adrenal cortex, liver and adipose tissue actively synthesize steroids and fatty acids – therefore PPP is dominant in these tissues. Other tissues such as skeletal muscle mostly lack the PPP.

39. FIGURE 14-20 General scheme of the pentose phosphate pathway. NADPH formed in the oxidative phase is used to reduce glutathione, GSSG (see Box 14-4) and to support reductive biosynthesis. The other product of the oxidative phase is ribose 5-phosphate, which serves as a precursor for nucleotides, coenzymes, and nucleic acids. In cells that are not using ribose 5-phosphate for biosynthesis, the nonoxidative phase recycles six molecules of the pentose into five molecules of the hexose glucose 6-phosphate, allowing continued production of NADPH and converting glucose 6-phosphate (in six cycles) to CO2.FIGURE 14-20 General scheme of the pentose phosphate pathway. NADPH formed in the oxidative phase is used to reduce glutathione, GSSG (see Box 14-4) and to support reductive biosynthesis. The other product of the oxidative phase is ribose 5-phosphate, which serves as a precursor for nucleotides, coenzymes, and nucleic acids. In cells that are not using ribose 5-phosphate for biosynthesis, the nonoxidative phase recycles six molecules of the pentose into five molecules of the hexose glucose 6-phosphate, allowing continued production of NADPH and converting glucose 6-phosphate (in six cycles) to CO2.

41. FIGURE 14-22 Nonoxidative reactions of the pentose phosphate pathway. (a) These reactions convert pentose phosphates to hexose phosphates, allowing the oxidative reactions (see Figure 14-21) to continue. Transketolase and transaldolase are specific to this pathway; the other enzymes also serve in the glycolytic or gluconeogenic pathways. (b) A schematic diagram showing the pathway from six pentoses (5C) to five hexoses (6C). Note that this involves two sets of the interconversions shown in (a). Every reaction shown here is reversible; unidirectional arrows are used only to make clear the direction of the reactions during continuous oxidation of glucose 6-phosphate. In the light-independent reactions of photosynthesis, the direction of these reactions is reversed (see Figure 20-10).FIGURE 14-22 Nonoxidative reactions of the pentose phosphate pathway. (a) These reactions convert pentose phosphates to hexose phosphates, allowing the oxidative reactions (see Figure 14-21) to continue. Transketolase and transaldolase are specific to this pathway; the other enzymes also serve in the glycolytic or gluconeogenic pathways. (b) A schematic diagram showing the pathway from six pentoses (5C) to five hexoses (6C). Note that this involves two sets of the interconversions shown in (a). Every reaction shown here is reversible; unidirectional arrows are used only to make clear the direction of the reactions during continuous oxidation of glucose 6-phosphate. In the light-independent reactions of photosynthesis, the direction of these reactions is reversed (see Figure 20-10).

42. FIGURE 14-16 (part 1) Opposing pathways of glycolysis and gluconeogenesis in rat liver. The reactions of glycolysis are on the left side, in red; the opposing pathway of gluconeogenesis is on the right, in blue. The major sites of regulation of gluconeogenesis shown here are discussed later in this chapter, and in detail in Chapter 15. Figure 14-19 illustrates an alternative route for oxaloacetate produced in mitochondria.FIGURE 14-16 (part 1) Opposing pathways of glycolysis and gluconeogenesis in rat liver. The reactions of glycolysis are on the left side, in red; the opposing pathway of gluconeogenesis is on the right, in blue. The major sites of regulation of gluconeogenesis shown here are discussed later in this chapter, and in detail in Chapter 15. Figure 14-19 illustrates an alternative route for oxaloacetate produced in mitochondria.

43. A -> B -> C -> D -> E; where the arrows represent an enzyme <- An example of a futile cycle would be if the paper from a pulp and paper mill were to be directed into a recycling plant that would reduce the paper back to pulp. Example of compartmentalization: fatty acids are synthesized in the cytosol and catabolized in the mitochondria.A -> B -> C -> D -> E; where the arrows represent an enzyme <- An example of a futile cycle would be if the paper from a pulp and paper mill were to be directed into a recycling plant that would reduce the paper back to pulp. Example of compartmentalization: fatty acids are synthesized in the cytosol and catabolized in the mitochondria.

44. Allostery: A change of shape, in this case of a molecule, that leads to a change in function. Second messenger signalling can include allostery. Which do you think exerts the tightest control? 3 < 2 < 1Allostery: A change of shape, in this case of a molecule, that leads to a change in function. Second messenger signalling can include allostery. Which do you think exerts the tightest control? 3 < 2 < 1

45. Note: Reactions 6 (glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase are coupled (refer to slide 17). Since the kinase reaction helps drive the dehydrogenase reaction, it can not be a site for regulation)Note: Reactions 6 (glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase are coupled (refer to slide 17). Since the kinase reaction helps drive the dehydrogenase reaction, it can not be a site for regulation)

46. Metabolism 320

48. hexokinase works at maximal activity with normal blood glucose levels -hexokinase works at maximal activity with normal blood glucose levels -