BIO 024- LESSON 9 ENZYMES 2.pdf

ENZYMES BIO 024 Lesson 9 Learning Targets: At the end of the module, students will be able to: 1. Define and know the importance of enzyme in our body; 2. Identify the nature enzymes; 3. Name the different structure of enzymes; 4. Identify the salient features of enzymes; and 5. Enumerate enzym...

ENZYMES BIO 024 Lesson 9 Learning Targets: At the end of the module, students will be able to: 1. Define and know the importance of enzyme in our body; 2. Identify the nature enzymes; 3. Name the different structure of enzymes; 4. Identify the salient features of enzymes; and 5. Enumerate enzymes containing metals. 6. Explain how enzymes are named; and 7. Identify the different classification of enzymes.  Enzyme is a complex organic compound E which has the ability of speeding chemical N reactions without itself being affected in the process. Z Y M E S  Enzymes are very specific ENZYMES and will only catalyze one specific chemical reaction. E The enzyme won’t change after the reaction takes place; it is recycled. N Z Y M E S ENZYMES In the absence of a specific enzyme, a reaction may hardly proceed at all. Structure of Enzymes Enzymes match with a substrate that fits like a puzzle at an active site. ⮚ The molecules that bind to the enzyme are called substrates. ⮚ The location where they bind (sit down) is called the active site. ⮚ After the enzyme and substrate bind it is called an enzyme- substrate complex. ⮚ The substrate may break apart or bond together to form a product. MODE OF ENZYME ACTION: 1. The surface of the substrate contacts a specific region of the surface of the enzyme molecule called active sites. 2. A temporary intermediate compound forms, called an enzyme-substrate complex. 3. The substrate is then transformed into products. 4. The products are released. 5. The enzyme is recovered unchanged. THE LOCK AND KEY MODEL Proposed by Emil Fischer in 1894. According to the model, the shape of the substrate and the active site of the enzyme are thought to fit together like a key into its lock. The two shapes are considered as rigid and fixed, and perfectly complement each other when brought together in the right alignment. THE INDUCED FIT MODEL Proposed by Daniel E. Koshland, Jr., In 1958. It states that the binding of substrate induces a conformational change in the active site of the enzyme. In addition, the enzyme may distort the substrate, forcing it into a conformation similar to that of the transition state.  COenzymes and Coenzymes are COFACTORS Cofactors may be organic molecules and organic or inorganic quite often bind loosely and do not bind with to the active site of an the enzyme. enzyme and aid in substrate recruitment.  NOMENCLATURE OF ENZYMES 1. Add -ase to the substrate e.g., carbohydrase, lipase, protease 2. Add -ase to the reaction catalyst e.g., oxidase, reductase, hydrolase Example: Lactase: the substrate catalyzed is lactose Maltase: the substrate catalyzed is maltose NOMENCLATURE OF ENZYMES As per system of nomenclature of enzymes, the name starts with EC (enzyme class) followed by 4 digits. ✔First digit represents the class ✔Second digit stands for the subclass ✔Third digit is the sub-sub class or subgroup ✔Fourth digit gives the number of the particular enzyme in the list.  NOMENCLATURE OF ENZYMES Consider this example: What is the name of the enzyme with the following characteristics? *acting on the CH-OH group of donors *with NAD+ or NADP+ as acceptor *alcohol dehydrogenase (NADP+) Step 1: Start with EC (enzyme class) Step 2: *acting on the CH-OH group of donors (subclass 1.1) *with NAD+ or NADP+ as acceptor (sub-sub class 1.1.1) *alcohol dehydrogenase NADP+ (particular enzyme 1.1.1.2 Examples of Biological Enzymes ⮚ Lipase — breaking down of fats (lipid) ⮚ Protease — breaking down of proteins ⮚ Cellulase — breaking down of fiber (cellulose) ⮚ Amylase — breaking down of starch (amylose) ⮚ Sucrase — breaking down of sugar (sucrose) ⮚ Maltase — breaking down of grains (maltose) ⮚ Lactase — breaking down of dairy products (lactose) FACTORS THAT INFLUENCE ENZYME ACTION: 1. Concentration of substrate 2. Concentration of enzyme 3. Temperature 4. pH 5. Presence of accelerators 6. Presence of inhibitors 7. Environmental hazards ACTIVITY TIME! Answer the Check For Understanding Activity found on page 7 of module #9.