Lecture Presentation Chapter 20 Enzymes and Vitamins Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 20 Enzymes and Vitamins A physician assistant (PA) helps a doctor by examining and treating patients as well as prescribing medications His or her duties may include obtaining patient medical records and histories, diagnosing illnesses, educating and counseling patients, and referring the patient, when needed, to a specialist General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 20 Readiness Core Chemistry Skills • • Interpreting Graphs (1.4E) Identifying the Primary, Secondary, Tertiary, and Quaternary Structures of Proteins (19.4, 19.5) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 20.1 Enzymes and Enzyme Action Enzymes are biological catalysts that • increase the rate of a reaction by changing the way a reaction takes place • • are not changed in the process of the reaction lower the activation energy of the reaction Learning Goal Describe enzymes and their role in enzyme-catalyzed reactions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake The enzyme carbonic anhydrase lowers the activation energy for the reversible reaction that converts CO2 and H2O to bicarbonate and + H © 2016 Pearson Education, Inc Enzymes Lower Activation Energy Enzymes increase the rate of a chemical reaction by reducing the energy required to convert reactant molecules to products An enzyme in the blood called carbonic anhydrase catalyzes • • + the rapid interconversion of carbon dioxide and water to bicarbonate and H + the reverse reaction, converting bicarbonate and H to carbon dioxide and water General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Enzymes and Active Sites Nearly all enzymes • are globular proteins with a unique three-dimensional shape that recognizes and binds a small group of reacting molecules, called substrates • have a tertiary structure that includes a region called the active site where one or more small groups of substrates bind to create a chemical reaction • have specific amino acid residues within the active site that interact with functional groups of the substrate to form hydrogen bonds, salt bridges, and hydrophobic interactions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Enzymes and Active Sites Enzymes like lactase have an active site where the substrate fits for catalysis to occur The quaternary structure of lactase consists of four subunits The substrate, lactose (gray), is held in place in the active site by hydrogen bonds with amino acid side chains General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Specificity of Enzymes • • • Some enzymes show absolute specificity by catalyzing only one reaction for one specific substrate Other enzymes catalyze a reaction of two or more substrates Some enzymes catalyze a reaction for a specific type of bond General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Enzyme-Catalyzed Reaction • • • The combination of an enzyme and a substrate forms an enzyme–substrate (ES) complex The ES provides an alternative pathway for the reaction with lower activation energy Within the active site, amino acid R groups catalyze the reaction to form an enzyme-product (EP) complex Core Chemistry Skill Describing Enzyme Action General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Enzyme–Substrate Complex A flexible active site in lactase and the flexible substrate lactose adjust to provide the best fit for the hydrolysis reaction Once the disaccharide is hydrolyzed, the monosaccharide products are released from the enzyme, which is ready to bind another lactose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Cobalamin, B12 Cobalamin, associated with methylcobalamin, • is found in liver, beef, kidney, chicken, fish, and milk products • has an RDA of 2.0–2.6 mcg • is necessary to avoid pernicious anemia, malformed red blood cells, and nerve damage General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Ascorbic Acid, C Ascorbic acid • is found in blueberries, citrus fruits, strawberries, cantaloupe, tomatoes, peppers, broccoli, cabbage, and spinach • has an RDA of 75–90 mg • is necessary to avoid scurvy: bleeding gums, weakened connective tissues, slow-healing wounds, and anemia General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Biotin, H Biotin, associated with biocytin, • is found in liver, yeast, nuts, and eggs • has an RDA of 30 mcg • is necessary to avoid dermatitis, loss of hair, fatigue, anemia, and depression General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify each enzyme as 1) a simple enzyme 2) an enzyme that requires a cofactor A requires Mg 2+ for hydrolysis of phosphate esters B requires vitamin B3 to transfer an acetyl group C is active with four polypeptide subunits General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Identify each enzyme as 1) a simple enzyme 2) an enzyme that requires a cofactor A requires Mg 2+ for hydrolysis of phosphate esters B requires vitamin B3 to transfer an acetyl group C is active with four polypeptide subunits General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Fat-Soluble Vitamins Fat-soluble vitamins • • • • include A, D, E, and K and are not involved as coenzymes in catalytic reactions are soluble in lipids but not in aqueous solutions are stored in the body and not eliminated in urine are important in vision, bone formation, antioxidants, and blood clotting General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Retinol (Vitamin A) Vitamin A, an antioxidant, • • • is needed for retinol (vision) and synthesis of RNA has an RDA of 800 µg is necessary to avoid night blindness, immune system repression, and slowed growth General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Cholecalciferol (Vitamin D) Vitamin D (D3) • • • • is synthesized in skin exposed to sunlight regulates the absorption of phosphorus and calcium during bone growth has an RDA of 5–10 μg is necessary to avoid weakened bones General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Tocopherol (Vitamin E) Vitamin E • • • • is an antioxidant in cells is found in whole grains and vegetables has an RDA of 15 mg is necessary to avoid hemolysis and anemia General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Menaquinon (Vitamin K) Vitamin K • • • is needed for the synthesis of zymogens for blood clotting has an RDA of 90–120 mcg is necessary to avoid prolonged bleeding time and bruising General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify each of the following as a water-soluble vitamin (WS) or fat-soluble vitamin (FS): A folic acid B retinol (vitamin A) C vitamin C D vitamin E E niacin General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Identify each of the following as a water-soluble vitamin (WS) or fat-soluble vitamin (FS): A folic acid WS B retinol (vitamin A) FS C vitamin C WS D vitamin E FS E niacin General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake WS © 2016 Pearson Education, Inc Study Check Identify the vitamin associated with each of the following: 1) riboflavin (B2) 3) vitamin K 2) vitamin A 4) vitamin D 5) ascorbic acid A collagen formation B part of the coenzymes FAD and FMN C absorption of phosphorus and calcium in bone D vision E blood clotting General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Identify the vitamin associated with each of the following: 1) riboflavin (B2) 3) vitamin K 2) vitamin A 4) vitamin D 5) ascorbic acid A collagen formation B part of the coenzymes FAD and FMN C absorption of phosphorus and calcium in bone D vision E blood clotting General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Concept Map General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... Quaternary Structures of Proteins (19 .4, 19 .5) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2 01 6 Pearson Education, Inc 20. 1 Enzymes and Enzyme Action Enzymes. .. bridges, and hydrophobic interactions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2 01 6 Pearson Education, Inc Enzymes and Active Sites Enzymes like... Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2 01 6 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2 01 6 Pearson Education,