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ENZYMES

ENZYMES. Biological Catalysts. Properties: - proteins - each enzyme controls a specific chemical reaction in living cells HIGHLY SPECIFIC - enzymes involved in a chemical reaction remain unchanged throughout the reaction. This makes them reusable!!!

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ENZYMES

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  1. ENZYMES Biological Catalysts

  2. Properties: - proteins - each enzyme controls a specific chemical reaction in living cells HIGHLY SPECIFIC - enzymes involved in a chemical reaction remain unchanged throughout the reaction. This makes them reusable!!! - these reactions must occur in a specific order and under exact conditions and not produce too much heat or the enzyme will be denatured or the cell destroyed. - enzymes can increase reaction rates up to a million times by lowering the activation energy( energy necessary to make the molecules react together) Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reactants Reaction pathway with enzyme Products

  3. - another name for a substance that increases reaction rates without being changed is a CATALYST ( enzymes are organic catalysts) - the substance an enzyme acts on is called a SUBSTRATE - enzyme names generally end in “ase” ex. Maltase- breaks down maltose into 2 glucose proteases- breakdown proteins lipases- breakdown lipids - enzymes are generally used in the cell they are made - enzymes sometimes need a non protein part to function called a COENZYME ex. Vitamin - they are reusable, but will eventually be broken down by the cell and new ones synthesized when needed

  4. How Do They Work ? • an enzymes shape is critical to its ability to react • most enzymes tend to be larger than the substances they react with, but only a small portion of the enzyme is actually involved in the reaction- THIS IS CALLED THE ACTIVE SITE. • *** THE ACTIVE SITE IS FORMED BY THE WAY THE POLYPEPTIDE CHAINSTWIST AND FOLD.

  5. Two Theories • Induced Fit Lock-n- Key • Specific for enzyme/ substrate - believes that each enzyme is • complex molecule formed when specific to only one substance • the two combine - the shape of the active site • Enzyme is not rigid and conforms allows only one type of sub- • to the substance much like a hand strate to bond • grasping an object - enzyme is a RIGID molecule

  6. Lock and Key vs Induced Fit Model of Enzyme Action

  7. Lock and Key Model

  8. Lock and Key Model

  9. Induced Fit Model

  10. Factors Affecting Enzyme Action There are many factors that can affect enzyme action in living cells. The rate may change but the products do not. A. TEMPERATURE: in general enzyme actions increase with an increase in temperature and vis versa BUT at a point enzymes will lose all effectiveness ( denaturation)- m the human body this occurs at about 40 degrees celcius.

  11. B. AMOUNTS OF ENZYME AND SUBSTRATE: enzyme action rate is affected by the amount of substrate present, meaning, if enzyme concentration is constant and substrate concentration is low- the reaction is constant, as substrate concentration increases the reaction rate increases and will continue until all enzymes are at their max and the reaction levels out

  12. C. pH : each enzyme acts best at a specific pH. ex. Pepsin( gastric protease) acts best at a pH of 2. It’s ineffective at neutral and basic pH’s. Trypsin is a pancreatic protease which acts best at basic pH’s( 8 or higher)

  13. Enzyme Inhibitors

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