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Enzymes
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  • 1. BY RIMSHA MUBASHIR ENZYMES
  • 2. ENZYMES  Enzymes are biological catalysts, mainly proteins, generated by an organism to speed up chemical reactions.  They can be described as any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions.  Biological catalysts are those catalysts which are found in living organisms and they speed up the metabolic reactions occurring in them.
  • 3. HISTORY OF ENZYMES Around late 17th and early 18th centuries, the digestion of meat by stomach secretions and the conversion of starch to sugars by plant extracts and saliva were known. However, the mechanism by which this occurred had not been identified.  In 1833, French chemist Anselme Payen discovered the first enzyme, diastase.  In 1877, German physiologist Wilhelm Kühne first used the term enzyme, which is Greek for "in leaven", to describe this process. It was later used to refer to nonliving substances, such as pepsin.
  • 4. Wilhelm Kühne
  • 5. CATALYSTS  A substance that lowers activation energy of a reaction so the reaction occurs more quickly but, in the end, is NOT used up by the reaction is called a catalyst.
  • 6. ACTIVATION ENERGY  To start any chemical reaction, energy is required. The minimum amount of energy required to start a reaction is known as it activation energy.  Activation Energy can be defined as the energy that must be added to cause molecules to react with one another.
  • 7. METABOLISM Metabolism can be described as a set of biochemical reactions on which the entire life of living organisms depend.  METABOLISM= Anabolism + Catabolism  CATABOLISM: biochemical reactions in which larger molecules are broken down.  ANABOLISM: biochemical reactions in which larger molecules are synthesized.
  • 8. This proves that biochemical reactions are actually energy transfers. Catabolism Energy is released Energy is gained Anabolism
  • 9.  Importance of Metabolism: Metabolism is very essential for carrying out all the life processes as a disturbed metabolic system can result in severe diseases and retardation.
  • 10. EXTRACELLULAR AND INTRA CELLULAR ENZYMES  Extracellular Enzymes: Enzymes that are produced inside cells but work outside them.  Intracellular Enzymes: Enzymes that work inside the cells.
  • 11. WHAT DO ENZYMES DO? Some of the ways in which enzymes react are:  Lowering the activation energy by creating suitable environment.  Bringing substrates together in the correct orientation to react. It forms ES complex for a while during the reactions.
  • 12. CHARACTERISTICS OF ENZYMES 1. Structure  Enzymes are globular complex protein structures made up of long linear chains of amino acid ranging from just 62 amino acid residues in size to over 2,500 residues.  Most enzymes are much larger than the substrates they act on.
  • 13. 2. Reactions  Unlike most catalysts enzymes are NOT consumed by the reactions they catalyze.  During reactions only a small area is directly involved. This area is called active site. • It is the region where the substrate is recognized and then bound for the reaction. Active Site • An enzyme substrate is the material upon which an enzyme acts. Substrate • A product is something "manufactured" by an enzyme from its substrate. Product
  • 14. 3. Cofactors There are some enzymes that need additional non protein molecules/ions called cofactors. Cofactors can be considered "helper molecules" that assist in biochemical transformations. Cofactor Organic Prosthetic Group: tightly packed Coenzyme: loosely attached Inorganic
  • 15. Enzymes Inactive Enzymes Apoenzymes/ Apoproteins: Need cofactors but don’t have any Active Enzymes Holoenzymes: Apoenzyme+cofactor
  • 16. 4. Metabolic Pathways When enzymes work together metabolic pathways are formed. In metabolic pathways a chain or path of reactions is formed.
  • 17. 5. Inhibitors Inhibitors are molecules that decrease enzyme activity. Many drugs and poisons are enzyme inhibitors.
  • 18. Some types of inhibitors are given here: Competitive :Substrate and inhibitor compete for the enzyme. Uncompetitive :The inhibitor cannot bind to the free enzyme, only to the ES-complex. Non-competitive : can bind to the enzyme at the binding site at the same time as the substrate, but not to the active site.
  • 19. 6. Activators Activators have the opposite effect on enzymes. They are the molecules that increase enzyme activity.
  • 20. WHAT FACTORS AFFECT ENZYMES? Enzymes are specific about the working conditions they are provided. Changes in the working conditions can change the type of enzyme, its active site or its speed. Some of the factors affecting enzyme activity are discussed here: 1. Temperature 2. pH 3. Substrate Concentration
  • 21. 1. Temperature Every enzyme works at its best when given a specific temperature. This temperature is called the optimum temperature of that enzyme. The optimum temperature of human enzyme is 37°C. Reactions are accelerated when the temperature rises to a certain limit .But when this limit is crossed denaturation of enzymes takes place.
  • 22. 2. pH Optimum pH is the range of pH at which enzymes work best. A slight change in this optimum pH causes: i).retardation in enzyme activity. ii).blockage of enzymes. iii).ionization of amino acids at the active sites.
  • 23. 3. Substrate Concentration If enzyme molecules are available in a reaction, increase in substrate concentration causes increase in the rate of reaction. If the ratio of enzymes is less than the ratio of substrates then the enzymes enter a state called saturation of active sites.
  • 24. HOW ENZYMES REACT?  Lock and Key Model: The enzyme and substrate are specific to each other. The active site of an enzyme fits together with a substrate like a lock and key. The key is the substrate and the lock is the enzyme.
  • 25.  Induced Fit Model: The enzyme is induced to undergo a slight alteration in order to fit with the substrate perfectly.
  • 26. USES OF ENZYMES IN DAILY LIFE Enzymes are produced in living organisms by cells but the enzymes used for commercial purposes are synthetic and made in industries. Enzymes are used in: 1. Bread production. 2. Fermentation. 3. Paper production. 4. Production of cleaning products (detergent etc.)
  • 27. Some Enzymes And Their Applications APPLICATION ENZYMES USED Food processing Amylase,Protease Baby food Trypsin Brewing industry Amylase,Protease Fruit juices Cellulase,Pectinases Dairy industry Lipases,Lactases Paper industry Amylase,Ligninase, Xylanases,Cellulases Biological detergent Amylase,Lipase,Cellulases Rubber industry Catalase Photographic industry Protease
  • 28. THANKS