Enzymes, coenzymes and isoenzymes
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The document discusses enzymes as biological catalysts that accelerate cellular processes, detailing their characteristics, classification, and functionality. It outlines how enzymes reduce activation energy to speed up reactions and introduces the Enzyme Commission's classification system. Additionally, it defines coenzymes, isoenzymes, and their respective roles in biochemical reactions.
Enzymes, coenzymes and isoenzymes
- 1. ENZYMES B Y O K E C H U K W U F R A N C I S ( M . S C )
- 2. • OBJECTIVES; • Definition of enzymes • Characteristics of enzymes. • Enzymes and how they work? • Classification of enzymes • Mode of actions of enzymes • Coenzymes • What are isoenzymes? Examples and roles in functional disorders.
- 3. ENZYMES are biological catalysts PRODUCED by biological cells, they speed up the rate of cellular processes or reactions. They are whole in form and can be easily destroyed by heat. Usually, a reaction like protein Hydrolysis (breakdown) by a strong acid at 100°c would take at least 24hours to complete but in the presence of the enzyme “Pepsin” in the intestine such reactions would take a matter of minutes. Imagine enzymes wasn’t present in our system, these reactions would delay for ages hence cells which require these nutrients obtained to survive would die before these nutrients gets to them.
- 4. • CHARACTERISTICS OF ENZYMES • Some general characteristics of enzymes includes; 1. All enzymes are protein in nature except RNA acting as Ribozymes. 2. Enzymes are specific in nature hence they all bind to a particular substrate. 3. Enzymes remains unchanged at the end of each chemical reactions hence the formation of the product from a certain substrate doesn’t affect the nature of an enzymes.
- 5. HOW ENZYMES WORK; Enzymes function by reducing the activation energy of a reaction (energy required to kick start a reaction), hence enzymatic process proceeds faster utilizing less energy as compared to a non-enzymatic process which would have to take more time for such high activation energy to be reached. A simple mechanism of bringing Both substrates and reaction Conditions to a closer contact Was best explained by the lock and Key model as seen in the diagram. Each enzyme has a specific Substrate it binds to, resulting in a Product synthesis.
- 6. • CLASSIFICATION OF ENZYMES; • Early enzymes to be isolated and named e.g trypsin, pepsin and chymotrypsin give no information about the reaction they catalyzed.This would create ambiguity in the nearest future hence in 1961 an enzyme commission was set up to develop a proper naming pattern for enzymes.This commission classified enzymes into 6 main classes according to the type of reaction they catalyzed. • The enzymes commission number format EC: a.b.c.d was also introduced where EC stands for Enzyme commission, a standards for main-class, b for sub-class, c for sub-sub class and d for position of the enzyme in the main class. • Hence an enzyme like lactase dehydrogenase which catalyzes the anaerobic production of lactic acid from pyruvate would have an enzyme commission number EC:1.1.1.27
- 7. 1. OXIDOREDUCTASES: ENZYMES INVOLVED IN OXIDATION-REDUCTION REACTIONS. Here gly-3-phosphate is reduced to 1,3 PGA IN AN OXIDOREDUCTION REACTION BY THE ACTION OF GLY-3- PHOSPHATE DEHYDROGENASE.
- 8. 2. TRANSFERASES: ENZYMES THAT CATALYZE THE TRANSFER OF FUNCTIONAL GROUPS.
- 9. 3. HYDROLASES: ENZYMES THAT BRING ABOUT HYDROLYSIS OF VARIOUS COMPOUNDS.
- 10. 4. LYASES: ENZYMES SPECIALIZED IN THE BREAK OR SPLITTING OF BONDS IN A PROCESS OTHER THAN HYDROLYSIS. Here fructose 1,6-bisphosphate is broken down to 2 triose phosphates namely without utilizing water like in hydrolysis.
- 11. 5. ISOMERASES: ENZYMES INVOLVED IN ISOMERIZATION REACTIONS. ENZYME NAME: PHOSPHOR TRIOSE ISOMERASE.
- 12. 6. LIGASES: ENZYMES CATALYZING THE SYNTHETIC TWO MOLECULES JOINED TOGETHER AND ATP IS USED. pyruvate is carboxylated in cellular organisms during gluconeogenesis and other metabolic processes by the enzyme pyruvate carboxylase in the presence of bicarbonate. ATP is utilized in this process.
- 13. COENZYMES/COFACTORS; • A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme’s activity. Cofactors can be considered "helper molecules" that assist in biochemical transformations.The rates at which these happen are characterized by enzyme kinetics.
- 14. ISOENZYMES; • These are oligomeric forms of more than one type of subunits, synthesized from different gene s but perform similar functions on the same substrate which is most often located in different organelles. A good example of an isoenzyme is lactate dehydrogenase which catalyzes the interconversion of pyruvate and lactic acid.