What are Enzymes? Enzymes are special types of proteins They speed up chemical reactions in cells by acting as biological “catalysts” –Involved in breaking bonds in the reactants and forming new bonds in the products of chemical reactions –Example: Breakdown of starch into simple sugars

What do Enzymes do? Enzymes play essential roles in: regulating chemical pathways. making material that cells need. releasing energy. transferring information.

How do Enzymes work? Enzymes speed up reactions when a substrate (molecule) binds to the enzyme’s active site (like a lock and key, or a puzzle piece). Enzymes can either break a substance down or link substances together through chemical reactions. Remember that Proteins do their jobs, because of their shape

Enzyme substrate complex Is formed when the enzyme binds to the reactant molecule. When the reaction is complete, the enzyme and the product molecule unbind and the enzyme is available for more reactions.

Hexokinase, an enzyme (blue), binding to its substrate, glucose (yellow). (The fit between enzymes & substrate is critical & precise

Enzyme Action Click on ENZYMES: The Basics – nimations/enzyme.html nimations/enzyme.html McGraw Hill Animation: – hill.com/sites/ /student_view0/chapter2/animatio n__how_enzymes_work.html hill.com/sites/ /student_view0/chapter2/animatio n__how_enzymes_work.html

EXAMPLE OF WHAT ENZYMES DO: Dehydration synthesis & also Hydrolysis Dehydration synthesis removes water to bond monomers to make polymers (builds up) Hydrolysis adds water in to a polymer to break it apart to form the monomers (breaks down) ehydrat.html ehydrat.html

Hydrolysis reaction 

Enzymes are biological Catalysts A substance that speeds up the rate of a chemical reaction. They work by lowering the reaction’s activation energy (which is the energy needed to get a reaction started.

Lowering activation energy with enzymes

Another Activation energy example

Metabolic pathways The synthesis of biological molecules often requires many enzyme-catalyzed steps. The entire set of steps is a metabolic pathway.

Types of Enzymes Lipase – Breakdown of fats. Protease – breaks down proteins.

Types of Enzymes Amylase- Breaks down starch into sugar. Polymerase- position and link DNA nucleotides together.

Types of Enzymes Helicase- unwinds DNA by breaking the hydrogen bonds.

Factors affecting enzyme action 1.Temperature – Disrupts hydrogen bonds, alters protein shape (denature) 2.pH – hydrogen ion concentration disrupts bonds between amino acids 3.Substrate Concentration – Increased substrate concentration increases reaction rate until all enzymes are involved, then reactions level out 4.Enzyme Concentration – Increased enzyme concentration increases reaction rate until all substrate is used up, then reactions decrease. These can denature the proteins (enzymes).

Some Diseases caused by lack of or malfunctioning enzymes PKU - missing phenylalanine hydroxylase (breaks down an amino acid called phenylalanine). Tay-Sachs – lack of Hexosaminidase (breaks down fatty substances, called GM2 gangliosides, in cells of the brain). Lactose Intolerance – reduction in production of lactase (breaks down lactose, milk sugar). Maple Syrup Urine Disease – lacks an enzyme to breakdown three different amino acids.

Activity: toothpickase Follow the directions on your handout to simulate enzyme action and understand the terms involved and what factors affect enzyme action. Be able to identify and describe the following terms: – Enzyme – substrate – Enzyme-substrate complex – Activation energy – Dehydration synthesis – Hydrolysis – Metabolism – Catalyst

 Take the name of the substrate the enzyme works on and add the suffix -ase  Example: Lactose  Lactase Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College

Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College