Lesson 11: Enzymes (PDF)

ENZYMES (Mechanisms and Factors influencing of Enzymatic Action, Clinical Enzymology)  LEARNING TARGETS Describe the mechanism action of enzymes Identify and explain the factors that affect enzyme activity and: Describe the medical applications of enzymes ARE YOU READY F...

ENZYMES (Mechanisms and Factors influencing of Enzymatic Action, Clinical Enzymology)  LEARNING TARGETS Describe the mechanism action of enzymes Identify and explain the factors that affect enzyme activity and: Describe the medical applications of enzymes ARE YOU READY FOR MY LESSON? MODE OF ENZYME ACTION:  THE PROCESS 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.  THE PROCESS 4. The products are released 5. The enzyme is recovered unchanged "Activation Energy: the minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport  THEORIES EXPLAINING THE MODE OF ENZYME ACTION 1 FISCHER'S LOCK AND KEY THEORY 2 KOSHLAND'S INDUCED FIT THEORY FISCHER'S LOCK AND KEY THEORY ALSO KNOWN AS ENZYME-SUBSTRATE (F-5) COMPLEX THEORY 1. The active site of the enzyme and substrate have complementary structures, hence they fit together as a key fits a lock 2. While they are bounded in the enzyme-substrate complex, catalytic reaction occurs 3. The products of the reaction leave the surface of the enzyme & combine with another molecule of the substrate FISCHER'S LOCK AND KEY THEORY General Reaction 1. E + S == E-S complex 2. ES complex - product + enzyme Example 1. sucrose + sucrase == sucrase-sucrose complex 2. sucrase-sucrose complex == glucose + fructose + sucrose FISCHER'S LOCK AND KEY THEORY  In this model, the substrate still needs to fit into the enzyme like a key, but instead of simply KOSHLAND'S INDUCED fitting into the keyhole, some FIT THEORY type of modification is induced in the substrate, enzyme, or both. The modification begins the process of the reaction  At first, substrate binds to a specific part of the enzyme. This leads to more secondary binding KOSHLAND'S INDUCED and conformational changes. FIT THEORY The substrate induces conformational changes in the enzyme, such that precise orientation of catalytic groups is effected FACTORS THAT INFLUENCE ENZYME ACTION 1. Concentration of substrate concentration of substrate = ↑enzyme action 2. Concentration of enzyme concentration of enzyme = ↑enzyme action 3. Temperature Optimum temperature of enzyme in the body = 37°C With each 10°C rise in temperature usually doubles or triples reaction rate Rapid inactivation of the enzyme occurs at temperatures much above body temperature Low temperatures slow down the action of enzyme but do not destroy them 4. pH level each enzyme has its specific optimum pH at which it exerts its maximum activity it loses activity rapidly on either side of this opt. Eg. Pepsin-1.5 to 2.2 Lactase-5.7 Trypsin-7.8 5. Presence of accelerators Activate the enzyme Eg. Metallic ions such as Ferrous, Ferric, Co, Mn, Mg, Mo 6. Presence of inhibitors Have the ability to combine with enzyme in a reversible and irreversible reaction and hence block enzyme catalysis Eg. Antibiotics- streptomycin Antienzymes-antitrypsin from 7. Environmental hazards Example: 1. Hg (Mercury) a. Hg from phenyl mercuric acetate Fungicide to prevent cellulose from rotting b. Methyl mercuric acetate Prevent rotting of seed grains 7. Environmental hazards 2. Cd (cadmium) Derived from cigarette smoke 1 pack = 15 mcg 3. Pb (lead) Present in gasoline  CLINICAL ENZYMOLOGY: Enzymes are commonly used in medicine as 1. Analytical tools or reagents in measuring quantities of various constituents in biologic fluids Eg. Urease, alcohol dehydrogenase CLINICAL ENZYMOLOGY:  CLINICAL ENZYMOLOGY: Enzymes are commonly used in medicine as 2. As index for pathology of diseases: Eg. of some serum enzymes  CLINICAL ENZYMOLOGY: a-amylase in pancreatitis normal serum level is elevated Lipase in acute pancreatitis, perforated duodenal and peptic ulcers and intestinal obstruction. Creatinine Phosphokinase (CPK) - ↑ in  CHECK FOR UNDERSTANDING LESSON #11 ACTIVITY Answer CHECK FOR UNDERSTANDING items 1 to 5 found on page 5 of your Session #11 module. Take a photo of you answered module and upload it in our GCR.