Energy Metabolism: Overview, Regulation, & Pathways

Faculty of Applied Health Sciences Department of Health Sciences Energy Metabolism 14  Faculty of Applied Health Sciences Department of Health Sciences Learning goals 1. Define metabolism and the important n...

Faculty of Applied Health Sciences Department of Health Sciences Energy Metabolism 14  Faculty of Applied Health Sciences Department of Health Sciences Learning goals 1. Define metabolism and the important nutritional components. 2. Identify and understand the fundamental reactions important to metabolism. 3. By following the flow of energy, understand the process of transferring energy from the food we eat. 4. Describe how metabolism changes after we eat, between meals, and after an extended fast (e.g. overnight). 5. Identifying the vitamins and minerals involved in metabolism and how they are associated to specific metabolic processes. 6. Identify the challenges associated with digestion and absorption of folate and B12 7. Discuss how to overcome nutritional challenges for nutrients discussed in this section as it relates to a vegan/vegetarian diet. 15  Faculty of Applied Health Sciences Department of Health Sciences Metabolism NEED TO KNOW THIS DEFINITION DEFINE: Sum of all chemical reactions in living cells Required to provide energy to the cells for growth, repair, maintenance, and reproduction All organs, tissues and cells have role in metabolism - Efficient process manufactures needed products and disposes wastes - Hormonal signals coordinate supply and demand In disease, metabolic processes can become disturbed - Some diseases caused by metabolic disturbances (e.g. diabetes) 17  Faculty of Applied Health Sciences Department of Health Sciences Metabolism Fundamental components – enzymes (proteins) - mediate metabolic reaction – coenzymes (vitamins e.g. niacin and riboflavin) - enhance or necessary for the action of enzymes – cofactors (minerals e.g. iron, zinc) - are required for enzyme activity Every chemical reaction either requires or releases energy – (form of ATP) 18  Faculty of Applied Health Sciences Metabolism Department of Health Sciences Fundamental chemical reactions 1. Condensation: (releases water and requires energy) 2. Hydrolysis (requires water and releases energy) 19  Faculty of Applied Health Sciences Department of Health Sciences The Body’s Metabolic Work Heat energy and body temperature Metabolic chemical reactions in cells release heat Keeps the body warm Regulating rate of reactions helps maintain constant normal temperature Accelerated metabolism Severe stress to body due to variety of stressors (such as burns, infection, surgery etc) increases metabolism Fuels used at faster than normal rate May result in fever, loss of weight and lean tissue 20  Faculty of Applied Health Sciences Department of Health Sciences The Body’s Metabolic Work Building Up Compounds Anabolism Energy-yielding nutrients used to build body compounds when not needed for energy Glucose units strung together to make glycogen chains Glycerol and fatty acids can be assembled into triglycerides Amino acids can be linked to form proteins Anabolic reactions require energy provided by ATP 21  In order to build up macronutrients you require energy Faculty of Applied Health Sciences Department of Health Sciences Anabolic reactions Anabolism NEED TO KNOW – making complex molecules from more basic ones – requires chemical energy – use condensation reactions (releases water) 22  Faculty of Applied Health Sciences Department of Health Sciences The Body’s Metabolic Work Breaking Down Compounds Catabolism: Breaking down of body compounds when the body needs energy Glycogen is broken down to glucose Triglycerides are broken down to fatty acids and glycerol Proteins are broken down to amino acids Catabolic reactions release energy 23  Faculty of Applied Health Sciences Department of Health Sciences KNOW THE DIFFERENCE BETWEENT HE TW Catabolic reactions Catabolism – breakdown of complex molecules to more basic ones – releases energy – use hydrolysis reactions (requires water) 24  Faculty of Applied Health Sciences Department of Health Sciences The Body’s Use of Fuels Key is understanding the metabolism, the chemical reactions that occur in all living cells. Energy manifests in many forms – Heat energy, mechanical energy, electrical energy, chemical energy – Energy is stored in foods and in the body as chemical energy 25  Faculty of Applied Health Sciences Department of Health Sciences Energy Metabolism Define: Sum of all reactions the body uses to obtain or expend energy from foods – Energy-yielding nutrients broken into basic units and absorbed into the blood: - glucose from carbohydrates - glycerol and fatty acids from fat - amino acids from proteins 26  Faculty of Applied Health Sciences Department of Health Sciences Energy Metabolism Adenosine Triphosphate (ATP) High-energy compound that contains 3 phosphate groups (Energy coin*) The bonds between the phosphate groups are described as high energy because of their readiness to release energy Transfers small amounts of usable energy to move our muscles Supplies enzymes with energy needed to catalyze chemical reactions Produced continuously throughout the day By using the energy from the break down of the energy- yielding nutrients 27  Faculty of Applied Health Sciences Energy comes from the macronutrients to synthesize ATP Department of Health Sciences Energy Metabolism Adenosine Triphosphate (ATP) 28  Faculty of Applied Health Sciences Department of Health Sciences Energy Metabolism The Chemical Pathways that produce ATP are: 1. Glycolysis (in cytoplasm, cytosol) 2. TCA Cycle (tricarboxylic acid cycle) (Krebs or citric acid cycle) (in mitochondria) 3. Electron transport chain (in mitochondria) D TO KNOW THE THREE PATHWAYS AND WHERE THEY OCCUR Know the ATP amount at each point and understand the basics of the cycle 29  Glycolysis Faculty of Applied Health Sciences Department of Health Sciences Glycolysis: Glucose (a 6-carbon compound) converted to pyruvate (a 3-carbon compound) producing 2 ATP , in cytosol (cytoplasm) (NEED TO KNOW THIS POINT) Carbons in glucose are broken apart to produce pyruvate Hydrogen atoms attached to the carbons are transferred by coenzymes to the electron transport chain After glycolysis, pyruvate converted to acetyl CoA (2 carbon fragment and a coenzyme called CoA which is derived from the pantothenic acid, B5 vitamin) in mitochondria 30  Faculty of Applied Health Sciences Department of Health Sciences Acetyl CoA - Fatty acids can be broken down into 2- carbon fragments that combine with CoA to form acetyl CoA - As carbons in fatty acids are broken apart to produce acetyl CoA, hydrogen atoms are released and transferred by coenzymes to the electron transport chain - Glycerol can also be converted to pyruvate and further to acetyl CoA - Amino acids can be converted to pyruvate then to glucose converted to acetyl CoA enter the TCA cycle Know where the acids go! 31  Faculty of Applied Health Sciences Department of Health Sciences TCA Cycle TCA cycle (tricarboxylic acid cycle), also known as the Krebs cycle or citric acid cycle Enzymes break down acetyl CoA to carbon dioxide and hydrogen atoms Hydrogen atoms are carried by coenzymes to electron transport chain Production of 2 ATP molecules This process takes place in mitochondria 32  Faculty of Applied Health Sciences Department of Health Sciences Electron Transport Chain ETC - Final step in energy metabolism Enzymes attach a phosphate group to ADP Creates max. 34 ATP using chemical energy provided by hydrogen atoms Hydrogen atoms linked with oxygen to produce water This process takes place in mitochondria 33  Energy Metabolism Faculty of Applied Health Sciences Department of Health Sciences Aerobic metabolism Production of ATP via electron transport chain Requires oxygen in final step Anaerobic metabolism Production of ATP through glycolysis (glucose to pyruvate) Does not require oxygen 34  Faculty of Applied Health Sciences Department of Health Sciences Glycolysis Glucose broken down into pyruvate Yields ATP and coenzyme (NADH) Complete oxidation results in 38 ATP (2 ATP from glycolysis, 2 ATP from TCA cycle and 34 ATP from electron transport chain) 35  Faculty of Applied Health Sciences Department of Health Sciences Know this! Carbohydrate Glucose Pyruvate 2ATP Acetyl-CoA TCA cycle ETC(34 ATP)→ 38 ATP 2ATP 36  Faculty of Applied Health Sciences Lipolysis Department of Health Sciences Glycerol converted to pyruvate – 3 carbon unit metabolized similarly to carbohydrates 37 Faculty of Applied Health Sciences Department of Health Sciences Glycerol Glucose Glycerol Pyruvate Acetyl-CoA TCA cycle ETC → ATP 38  Faculty of Applied Health Sciences Department of Health Sciences Lipolysis Fatty acids can be converted to acetyl-CoA 39 Faculty of Applied Health Sciences Department of Health Sciences Fatty acids Glucose Glycerol Pyruvate Acetyl-CoA Fatty acids TCA cycle ETC → ATP 40  Faculty of Applied Health Sciences Department of Health Sciences Amino acids Deamination – removal of amine group (NH2) from amino acid to form a keto acid – amino group converted to ammonia (NH3); ammonia converted to urea in liver and excreted by kidney – deamination occurs primarily in the liver 41  Faculty of Applied Health Sciences Department of Health Sciences Amino acids Point of entry of keto acids – If converted to pyruvate called glucogenic – If converted to acetyl-CoA called ketogenic – Some can directly enter the TCA cycle 42 Faculty of Applied Health Sciences Department of Health Sciences Amino acids Glucose Glycerol Amino acids Pyruvate Amino acids Acetyl-CoA Fatty acids Amino acids TCA cycle ETC → ATP 43  Faculty of Applied Health Sciences Department of Health Sciences Glucose Production Glucose produced from non-carbohydrate sources by gluconeogenesis In response to decreased glucose levels Any compound that can be converted to pyruvate can be used to make glucose NOTE: Compounds that are converted to acetyl CoA cannot be used to make glucose 44  Faculty of Applied Health Sciences Department of Health Sciences Glucose Production Triglycerides consist of three fatty acids and a glycerol Fatty acids break down to acetyl CoA Cannot be used for glucose production Glycerol portion can be converted to pyruvate and can yield glucose Glycerol represents small percentage of weight of total triglyceride molecule Fat is an inefficient source of glucose (IMPORTANT) 45  Faculty of Applied Health Sciences Department of Health Sciences Glucose Production Primary role of amino acids Maintain body protein supply To be used as energy source, must undergo deamination (removal of amine group from amino acid) After deamination, amino acids can be converted to pyruvate and be used to provide glucose Fairly efficient source of glucose when carbohydrate is not available 46  HOW CAN GLUSOCE BE PRODUCE BY OTHER THI Faculty of Applied Health Sciences Department of Health Sciences Gluconeogenesis Glucose can be produced by other compounds (MACRONUTRIENTS) through gluconeogenesis – glucogenic amino acids – glycerol Understand the process and the difference between the two 47  HOW LIPIDS ARE BEING PRODUCED BY OTHER THI Faculty of Applied Health Sciences Department of Health Sciences Lipogenesis Lipids can be produced by other compounds through lipogenesis – glucose – ketogenic amino acids 48  HOW AMINO ACIDS CAN BE PRODUCED WITHIN THE BO Faculty of Applied Health Sciences Department of Health Sciences Amino acid synthesis Amino acids can be produced from other amino acids through transamination – amino acid transfers amine group to keto acid, and a new amino acid and keto acid are formed 49  Faculty of Applied Health Sciences Understand and Know this chart Department of Health Sciences Summary Nutrient Yields energy Feeds into Feeds into Feeds into as ATP? glucose non-essential fatty acid production? amino acid production? (glucose production? (Fatty acid Production) (AA production) Production) Glucose Yes Yes Yes2 Yes Fatty acid Yes NO NO Yes Glycerol Yes Yes1 Yes2 Yes Amino acid Yes Yes1 Yes Yes 1 If CHO unavailable to cells 2 If source of nitrogen available, via pyruvate which is produced from glucose and glycerol, pyruvate can make amino acid 50 alanine  Faculty of Applied Health Sciences Stored in the adipose tissue as triglycerides Department of Health Sciences Feasting Consumption of more energy than is expended Much of excess stored as body fat Fat can be made from any energy-yielding nutrient Fat cells (adipose tissue) enlarge as they fill with fat 51  Faculty of Applied Health Sciences Department of Health Sciences Feasting CHO – after adequate liver and muscle glycogen stores, excess burned for energy and displaces use of fat for energy allowing body fat to accumulate (Stored as glycogen in liver and muscle for normal amounts) Lipids – excess fat adds to body fat stores, stored in adipose tissue until needed for energy Protein – after used for growth, repair, and maintenance, excess can be converted to triglycerides and also deaminated and burned for energy 52  Faculty of Applied Health Sciences Department of Health Sciences Fasting Energy needs normally met by periodic refueling (eating several times a day) When food is not available, body uses fuel reserves from tissues – Carbohydrate and fat stores used first – Body begins using protein stores within two days 53  Faculty of Applied Health Sciences Department of Health Sciences Fasting – acute (Short-term) CHO – liver and muscle glycogen broken down and used for energy by brain, nervous system, RBC and other cells Lipids – fatty acids released and used for energy by rest of body 54  Faculty of Applied Health Sciences Most important is the creation of the KETONE BO Department of Health Sciences Prolonged fasting CHO – none remaining Lipids – some fatty acids converted to ketone bodies to supply brain, remainder of fatty acids released and used for energy by rest of body Protein – lean tissue broken down and amino acids deaminated for gluconeogenic and ketogenic purposes 55  Faculty of Applied Health Sciences Department of Health Sciences How do we regulate metabolism? Coenzymes – assist in the production of energy – many coenzymes contain B vitamins as part of their structure, and also some B vitamins are converted to coenzymes Coenzyme: small molecule that combines with enzyme to make it active 56  DO NOT NEED TO MEMORIZE THIS BUT IT DOES SUMMARIES THE NEXT S Faculty of Applied Health Sciences Department of Health Sciences Note: many coenzymes contain B vitamins as part of their structure, and also some B vitamins are 57 converted to coenzymes  Faculty of Applied Health Sciences DO NOT NEED TO MEMORIZED Department of Health Sciences Coenzymes Protein Metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin acid panthothenic folate B12 B6 niacin acid niacin B12 TCA Cycle ETC niacin riboflavin niacin riboflavin biotin 58 In general: Know the Vitamin the corresponding coenzyme what is plays a role in and the sources  Faculty of Applied Health Sciences Need to know in RED (and know the examp Department of Health Sciences Thiamin (B1) Involved in CHO metabolism Protein metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin Thiamine pyrophosphate (TPP) acid panthothenic folate B12 B6 niacin acid niacin B12 which is derivative of thiamine and produced by the enzyme thiamine TCA Cycle ETC diphosphokinase, functions as a niacin riboflavin niacin riboflavin coenzyme in CHO metabolism biotin Good sources include – pork – legumes – sunflower seeds – whole grain breads 59  Faculty of Applied Health Sciences KNOW THE THE RED AND SOURCES Department of Health Sciences Riboflavin (B2) It is precursor of the coenzyme Flavin Adenine Dinucleotide Protein metabolism CHO metabolism Lipid metabolism (FAD) and Flavin niacin B6 thiamin riboflavin B12 riboflavin panthothenic acid Mononucleotide (FMN) panthothenic folate B12 B6 niacin acid niacin B12 Involved in CHO and lipid TCA Cycle ETC metabolism, TCA cycle and ETC niacin riboflavin niacin riboflavin Good sources include biotin – dairy – meat – eggs Need to know Vitaim, the coenzyme and the – green vegetables sources – whole-grain breads 60  Faculty of Applied Health Sciences Niacin (B3) Department of Health Sciences Precursor for the synthesis of coenzymes NAD and NADP Protein metabolism CHO metabolism Lipid metabolism Involved in protein, CHO and lipid panthothenic niacin B6 thiamin riboflavin B12 riboflavin acid metabolism, TCA cycle and ETC panthothenic folate B12 B6 niacin acid niacin B12 Amino acid tryptophan can be TCA Cycle ETC converted to niacin: 60 mg niacin riboflavin niacin riboflavin tryptophan = 1 mg NE (niacin biotin equivalents) Good sources include – meat – fish – peanut butter – whole-grain bread – certain vegetables (e.g. 61  Faculty of Applied Health Sciences Department of Health Sciences Pyridoxine (B6) Part of protein and CHO metabolism Protein metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin acid Pyridoxal phosphate (PLP) folate B12 B6 niacin panthothenic acid niacin B12 coenzyme is the active form of B6 TCA Cycle ETC niacin riboflavin niacin riboflavin Good sources include biotin – protein-rich foods (e.g. poultry, meat, fish) – certain fruits (e.g. bananas) and vegetables (e.g. spinach) 62  Faculty of Applied Health Sciences Department of Health Sciences Folate Part of protein metabolism Good sources include: Protein metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin Beef liver, legumes (e.g. lentils), acid panthothenic folate B12 niacin acid niacin B12 B6 beets, leafy green vegetables TCA Cycle ETC niacin riboflavin niacin riboflavin biotin 63  NEED TO KNOW (occurs naturally in foods) Faculty of Applied Health Sciences Folate Department of Health Sciences Two forms – folate - naturally occurring in foods – folic acid – dietary supplements and fortified foods Folate and folic acid are converted to coenzyme tetrahydrofolate (THF) which is involved in protein metabolism Folate and vitamin B12 work closely together 64  Faculty of Applied Health Sciences Department of Health Sciences Vitamin B12 Involved in protein, CHO and lipid metabolism and folate Protein metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin interaction acid panthothenic folate B12 B6 niacin acid niacin B12 Acts as a coenzyme TCA Cycle ETC niacin riboflavin niacin riboflavin Good sources include biotin – animal foods e.g. red meat, dairy – fortified cereals 65  Faculty of Applied Health Sciences Department of Health Sciences Vitamin B12 (cont’) Absorption is complex – B12 binds to animal protein in the diet – re-binds to an R protein (secreted by salivary glands, binds in stomach) – is released from R protein and binds to intrinsic factor (secreted by stomach) in the small intestine – intrinsic factor releases B12 into the intestinal cells know the salivary gland products R protein and binds to B12 in stomach 66 2 is release then is bind to intrinsic factor (released from stomach) in SM and then is released for absorptio  Faculty of Applied Health Sciences Department of Health Sciences Vitamin B12 -Vegetarian/Vegan diet ??? Inadequate intake of challenges B12 especially in vegans Almost exclusively from animal foods – Intakes adequate for meat- eaters and lacto-ovo vegetarians 67  Faculty of Applied Health Sciences Department of Health Sciences Others Pantothenic acid – involved in CHO and lipid metabolism Protein metabolism CHO metabolism Lipid metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin – key precursor for the biosynthesis acid panthothenic folate B12 B6 niacin acid niacin B12 of coenzyme A (CoA) TCA Cycle ETC Biotin niacin riboflavin niacin riboflavin – involved in TCA cycle biotin – acts as a coenzyme Sources: Both widespread in foods (e.g. eggs, vegetables), no danger of deficiency with varied diet 68  Faculty of Applied Health Sciences Department of Health Sciences Minerals Roles in hormonal regulation and enzyme structure – sulfur/sulfate – iodine 69  Faculty of Applied Health Sciences Department of Health Sciences Sulfur/Sulfate Sulfate: oxidized form of sulfur which exists in food and water Sulfur-containing amino acids play role in shaping strands of protein by forming sulphur-sulphur bridges – Protein’s shape enables it to perform specific function such as enzyme work Component of B vitamins (thiamin, biotin) and the hormone insulin Significant food sources: all protein containing foods (meats, fish, poultry, eggs, milk, legume, nuts) No recommended intake/ No known deficiencies 70  Faculty of Applied Health Sciences Iodine Department of Health Sciences Integral part of thyroid hormones, which regulate: – Body temperature – Metabolic rate(weight control) – Reproduction – Growth – Manufacture of blood cells – Muscle and nerve function Deficiency – Enlargement of thyroid gland (simple goiter) Sources – Seafood – Dairy – Present in soil in which plants are grown – Iodized salt-salted foods (primary source for Canadians) 71  Faculty of Applied Health Sciences Need to know co-enzyme, metabolism Department of Health Sciences and the sources for each of the vitamins and minerals This is the summary of everything Summary Thyroid hormones iodine Protein metabolism CHO metabolism Fat metabolism panthothenic niacin B6 thiamin riboflavin B12 riboflavin acid panthothenic folate B12 B6 niacin acid niacin B12 * sulfur TCA Cycle ETC niacin riboflavin niacin riboflavin biotin 72 Faculty of Applied Health Sciences Department of Health Sciences Oxidative Protection 73  Faculty of Applied Health Sciences Department of Health Sciences Learning goals 1. Define free radicals and describe their source as it relates to metabolism. 2. Define antioxidants and how they interact with free radicals. 3. List the antioxidant vitamins and describe how they contribute to oxidative protection. 4. List the antioxidant minerals and describe how they contribute to oxidative protection. 74  Faculty of Applied Health Sciences Department of Health Sciences DO NOT WANT- CAUSES DAMAGES 75  Faculty of Applied Health Sciences Department of Health Sciences Sources of free Radicals production: - Endogenous (e.g. metabolism, even exercise can cause some) - Exogenous (e.g. pollution, smoking) She talked about the bottom diagram as examples, maybe important 76  Faculty of Applied Health Sciences Department of Health Sciences Free Radicals and Reactive Oxygen Species (ROS) Same thing but the ROS are also free radicals but always contain oxygen. 77  Faculty of Applied Health Sciences Department of Health Sciences - The reduction of molecular oxygen (O2) by accepting a single electron during metabolism produces superoxide - Superoxide is the precursor of most other reactive oxygen species (ROS) 78  Faculty of Applied Health Sciences Department of Health Sciences Oxygen & Superoxide When an oxygen accepts a single electron during metabolism it becomes superoxide Oxygen Superoxide 79  Faculty of Applied Health Sciences Department of Health Sciences When you loss an electron When you get an electron Oxidation-Reduction 80 Faculty of Applied Health Sciences Department of Health Sciences 81  Faculty of Applied Health Sciences Department of Health Sciences Problems in the balance cause the problems listed within the images 82  Faculty of Applied Health Sciences Department of Health Sciences Antioxidants Define: A substance in foods that significantly decreases the adverse effects of reactive species on normal physiological function – Antioxidants (e.g. vitamins- donate electron to stabilize free radical) Minerals - convert free radical to less damaging substances 83  Faculty of Applied Health Sciences Department of Health Sciences Vitamin E – αlpha-tocopherol - biologically active form – lipid soluble - Antioxidant Protects other (cell membranes) substances from oxidation by being oxidized itself Protects lipids and other components of cell membranes Especially effective in preventing oxidation of polyunsaturated fatty acids 84  Faculty of Applied Health Sciences Department of Health Sciences Vitamin E Widespread in foods Good sources include for example: – vegetable oils – margarine – nuts (e.g. almonds) and seeds (e.g. sunflower seeds) – whole grain products – green and leafy vegetables 85  Faculty of Applied Health Sciences Department of Health Sciences Vitamin C – water soluble – Antioxidant: protects water-soluble substances and some fat-soluble compounds (e.g. Vitamins A and E) from oxidation by being oxidized itself – it can regenerate oxidized molecules (e.g. oxidized Vitamin E, oxidized iron etc) to their original active forms – RDA recommends more for smokers – Good sources include for example: citrus fruits, red peppers, strawberries, broccoli etc Do not need to know the milligrams of the sources 86  Faculty of Applied Health Sciences Department of Health Sciences Vitamin A Lipid soluble Three forms of Vitamin A serve different functions – Retinol – Retinal – Retinoic acid Do not need to know about the diagram 87  Faculty of Applied Health Sciences Department of Health Sciences Vitamin A and Beta-Carotene Beta-carotene – Plant-derived Vitamin A precursor – Extremely effective antioxidant – No RDA for beta-carotene – Food (e.g. plants with deep orange pigments and dark green vegetables) is best source (not supplements) 88  Faculty of Applied Health Sciences Department of Health Sciences Antioxidants “A substance in foods that significantly decreases the adverse effects of reactive species on normal physiological function” Vitamins - donate electron to stabilize free radical Minerals - convert free radicals to less damaging substances 89  Faculty of Applied Health Sciences Department of Health Sciences Minerals Act as cofactors to enzymes that convert free radicals to less damaging substances For example, manganese, zinc and copper in superoxide dismutase (SOD), iron in catalase and selenium in glutathione peroxidase 90 Faculty of Applied Health Sciences Understand and be able to example Department of Health Sciences Co-Factor (Magnesium , copper Co-factor Co-Factor and zinc) (IRON) (Selenium) ROS Know the three enzymes and know the minerals that are co- factors for these enzymes 91 Faculty of Applied Health Sciences Department of Health Sciences 92  Faculty of Applied Health Sciences Know these examples Department of Health Sciences Enzyme #1- Superoxide dismutase (SOD) Enzyme which converts free radical (superoxide, O2-) to oxygen (O2) and hydrogen peroxide (H2O2) In humans there are 2 forms – contains manganese (e.g. nuts, leafy green vegetables etc) Mn-SOD mitochondrial – contains copper (e.g. seafood, nuts, seeds etc) and zinc (e.g. seafood, meats etc) Cu-Zn-SOD 93 cytosolic and extracellular  Faculty of Applied Health Sciences Department of Health Sciences Enzyme #2- Catalase Protect the cell from the toxic effects of hydrogen peroxide (H2O2) Catalase contains four heme (iron) rings which pull electrons away from H2O2 bonds, causing it to disassociate 2H2O2 → 2H2O + O2 Fe-Catalase Iron significant food sources: red meats, fish, poultry, shellfish, eggs, legumes, dried fruit (will talk more about this in next lecture) 94  Faculty of Applied Health Sciences Department of Health Sciences Enzyme #3- Glutathione peroxidase – Selenium works as part of glutathione peroxidase enzyme which converts hydrogen peroxide into water and oxygen – Significant sources: seafoods, meats, whole grains and vegetables 95