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Enzymes Honors Biology 2009 Hydrogen Peroxide H2O2 H-O-O-H Antiseptic – kills infective organisms? Cells produce as a waste (poison) Body enzymes (chemicals) can break it down, make it harmless Produced by? Liver Liquid (liver added) bubbles (gas) + liquid H2O2 H20 + O2 (toxic) Enzyme (harmless) Hydrogen peroxide in tooth whitening products Oxygen reacts with deposits on teeth to remove them Types of Chemical Reactions (changes) Decomposition – break down; break molecules apart Examples: H2O + O2 A. H2O2 B. Starch to what? glucose, using salivary mouth enzyme amylase; also produced by pancreas C. Lipid (fat) to what? fatty acids + glycerol, using lipase produced by pancreas and small intestine D. Proteins to what? amino acids, using pepsin produced by stomach finished in small intestine using proteases Synthesis – join small molecules to make larger ones What type of chemical reaction is often involved? Dehydration synthesis (water removal) Examples: A. amino acids B. glucoses protein di- and poly-saccharides (maltose, starch) C. fatty acids + glycerol lipid (fat) D. photosynthesis (light/to join) CO2 + H2O C6H12O6 + O2 Decomposition or Synthesis? Synthesis Dehydration Decomposition Hydrolysis Catalysts and Enzymes Some chemical reactions can be speeded up by heating; not always possible in an organism Catalyst - Something that can speed up a chemical reaction Chemical reactions often need a “boost” (energy input) to occur Activation Energy What acted as catalysts in our lab and demos? Manganese dioxide MnO2 (inorganic) Liver Enzyme – catalyst of living origin - organic (cells) Catalysts and enzymes can lower the activation energy allowing reactions to occur, often at a lower temperature (Ex: 98.60) Enzymes for decomposition of Hydrogen Peroxide Plant - peroxidase Liver – catalase Characteristics of Enzymes 1. Organic (living things) origin Lab Results: “New” Liver + “New” peroxide Reaction? Yes “Old” Liver + “New” peroxide Reaction? Yes 2. Enzymes are not changed by the reaction in which they participate; can be reused Lab Results: “New” Liver + “old” Liquid (O2 and H2O) Reaction? No Why not? Peroxide already broken down 3. Enzymes can speed up both decomposition and synthesis reactions. Can break apart or join things together (Judge – can marry or divorce) Sometimes, not always, one enzyme can do both. Ex. A (glucose) + B (fructose) enzyme #1 AB (sucrose) synthesis Ex. AB (sucrose) Enzyme # 1 or another? A (glucose) + B (fructose) decomposition If enzyme # 1 can do both…….. AB (sucrose) A (glucose) + B (fructose) 4. Enzymes are themselves, made of protein. Huge chains of amino acids that coil into specific shapes with a specific bonding areas called: Active Sites (like one piece of a puzzle) 5. Enzymes are specific (picky) about what chemicals they act upon (specificity) (again, two puzzle pieces) Called: Lock and key hypothesis Chemicals acted upon = substrate Ex. Enzyme that could decompose sucrose into glucose and fructose has an active site that only fits/bonds to sucrose, not starch, protein or fat, etc. Ex. Enzyme that joins glucose and fructose to make sucrose When enzyme and substrate bond for the reaction, forms enzyme-substrate complex 6. Usually, not always, enzymes are named after the substrate upon which they react, followed by suffix - ase Ex. Peroxidase – acts on peroxide Sucrase – acts on sucrose Lipase – acts on lipids Proteases – act on proteins Ex. An exception Amylase – acts on starch 7. Enzymes act best at specific temperatures. Lab Results: A. Liver + peroxide at room temperature Reaction? B. Liver + peroxide at high (65 degree) temperature Reaction? C. Liver + peroxide at body (37 degree) temperature Reaction? D. Liver + peroxide at cold (0 to 5 degree) temperature Reaction? Human body (98.60 F or 370 C) Enzymes are protein which denatures (unravels) at non ideal temperatures, destroys active site Why do high fevers make us feel so sick and can be fatal? 8. Enzymes function best at specific pH levels. Lab results: A. Liver + peroxide with pH of 4 pH? Should be acid Reaction? B. Liver + peroxide with pH of 7 pH? Should be neutral Reaction? C. Liver + peroxide with pH of 10 pH? Should be basic/alkaline Reaction? Ideal pH can vary greatly from one enzyme to another Ex: Stomach enzymes need acidic pH of about 1-2 Some stomach cells are modified to secrete acid Can secrete too much and cause acid reflux into food pipe (esophagus) May need drugs to reduce acid production – Prilosec, Nexium, Zantac Or, take a base to neutralize the acid – Tums, Rolaids (Antacids) Small intestine enzymes won’t function in acid What would need to be added to the food as it moves into intestine from stomach? Base – added by pancreas and small intestinal cells Ex: Enzymes in blood like a pH of 7.4 (Blood clotting proteins) Cut E1 E2 E3 etc....................................E13 Clot Most hemophiliacs (bleeding disorder) are missing enzyme # 8 9. Some enzymes need a “helper” and cannot function without it. May be non protein and non organic, called cofactors Ex: ions of Zinc, Iron, Copper If organic (contain Carbon), called coenzymes Most are vitamins themselves or made from vitamins Ex: Vitamin B6 needed for enzymes to convert one amino acid to another Ex: Coenzyme Q 10 helps cells produce energy Protects cell membranes from damage that can lead to aging or even cancer It decreases in bodies as we age Supplements 10. Enzymes can sometimes be “shut down” by other chemicals called: Inhibitors. Ex: Many insecticides contain inhibitor chemicals to shut down enzymes used for transmitting nervous messages. Ex: Some drugs to treat HIV infection contain inhibitors to stop the virus from reproducing Summary of Enzyme Function Enzymes and Human Digestion Four main stages of food processing 1. Ingestion – to take into body 2. Digestion – to chemically decompose 3. Absorption – to take into bloodstream 4. Elimination – to remove waste (feces) What needs to be digested? Carbohydrates, Lipids, Proteins Human Digestive Anatomy Pathway of Food Mouth – Ingestion (Salivary Glands) – dump enzymes into mouth; Digestion Esophagus Stomach – Digestion by producing enzymes (Pancreas) – dumps enzymes and buffer base into small intestine (Liver) – dumps bile into small intestine Small Intestine – Digestion (produces enzymes) and Absorption Large Intestine – Absorption of water and elimination Accessory Digestive Organs Food Pathway and Enzymes Mouth salivary glands secrete: Salivary amylase – starts polysaccharide breakdown into disaccharides Ex: starch to maltose Stomach cells secrete: Acid – Why? Lowers pH and kills bacteria Mucus – Why? Protects stomach lining Pepsinogen which is converted to pepsin in acid Begins protein digestion Stomach takes 2-6 hours to empty Chyme = stomach contents Liver Dumps bile into small intestine (stored in gall bladder) Bile begins Lipid break down into droplets (emulsify) Small Intestine cells secrete: A base (buffer) Why? Neutralize acidic chyme Pancreas Dumps enzymes into small intestine Small intestine and pancreas both produce various Enzymes: I. Pancreatic amylase – continues starch breakdown II. Maltase – breaks maltose into 2 glucoses III. Lactase – breaks lactose into glucose and galactose (Lactose intolerance) IV. Sucrase – breaks sucrose into glucose and fructose V. Proteases – continue protein break down into amino acids VI. Lipases – continue lipid breakdown into fatty acids and glycerol Small intestine absorbs small particles Large Intestine No enzymes secreted Absorbs most of the water to form feces Absorbs tiny ions like calcium (Ca++) and sodium (Na+) – electrolytes Elimination of feces through rectum and anus