Apple Experiment Come down and get an apple and a slice of lemon. When you get back to your seat: 1. Take a big bite of your delicious apple. 2. Immediately squeeze lemon juice over the apple flesh that is now exposed from the bite. 3. IMPORTANT! Don’t get lemon juice all over the apple. Make sure that it is ONLY on the area that you just bit! 4. Set the lemon aside and wipe any lemon juice off of your hands with a napkin. 5. Take another bite from the opposite side of your apple. 6. Set your apple aside.

Lecture 4: Enzymes

What Are Enzymes? Enzymes are __________ (tertiary and quaternary structures). An enzyme is a _________ in cellular reactions. A catalyst accelerates a reaction. proteins catalyst

Enzymes Are ________ for what they will catalyze Are _________ Usually end in -_____ -Sucrase -Lactase -Maltase specific reusable ase

How do enzymes work? Each enzyme has a unique 3-D shape, including a surface groove called an ______ _____. The enzyme works by binding a specific chemical reactant (_________) to its active site, causing the substrate to become unstable and react. The resulting __________ is then released from the active site. Active site Substrate Product

How do enzymes work? Enzymes work by _______ ______ which ________ activation energy. Weakening bonds Lowering

Enzyme-Substrate Complex The reactant an enzyme acts on is specifically called the _________. Enzyme Joins Substrate Substrate

______ _____ Enzyme Active Site Substrate A specific region of an enzyme molecule which binds to the substrate. Active Site Enzyme Substrate Active site

Shape of a Protein An enzyme fits with its substrate like a ____ and ____. Lock Key

EnzymeAnimation : Gary E. Kaiser http://student. ccbcmd EnzymeAnimation : Gary E. Kaiser http://student.ccbcmd.edu/biotutorials/proteins/enzsub.html View : http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

Enzymes are ____ ________ in the reactions they catalyze Enzymes are ____ ________ in the reactions they catalyze. Think of them as tiny machines in manufacturing. The more machines, the faster the accumulation of _________. Not consumed Product Image: Wine Bottling : www.morrison-chs.com/timingscrews/index.html Wine Vats: www.lymebaywinery.co.uk/pages/about_us.htm

Formats for writing a chemical reaction. ( ________ ) _______ + ________ -----------> _________ __________ -----------> ________ ________ Reactant, reactant, (enzyme) > product Reactant, (enzyme) > product, product One or more of the reactants in an enzymatic reaction is the substrate, the reactant(s) that specifically interacts with the enzyme.

4 levels of Protein Structure

How Do You Stop an Enzyme? _______________ • Alteration of a protein shape through some form of external stress • Denatured protein can’t carry out its cellular function . Denaturation Irreversible egg protein denaturation caused by high temperature (while cooking it).

Factors Affecting Enzyme Activity Temperature pH Cofactors & Coenzymes Inhibitors

Temperature & pH Think about what kind of cell or organism an enzyme may work in… Temperatures far above the normal range _________ enzymes (This is why very high fevers are so dangerous. They can cook the body’s proteins) Most enzymes work best near __________ pH (6 to 8). Denature Neutral

Coenzymes & Cofactors Non-protein substances (zinc, iron, copper, vitamins) are sometimes need for proper enzymatic activity. • Coenzyme versus Cofactor: What’s the dif? _________ more general term. Includes inorganic and organic molecules. _________ type of Cofactor, But specifically organic molecules. Cofactor Coenzyme Image: EnzymeCofactor : Public domain Wiki, Ribbon-diagram showing carbonic anhydrase II. The grey sphere is the zinc cofactor in the active site.

Coenzyme : Vitamin B12 Example: Most _________ are coenzymes essential in helping move atoms between molecules in the formation of carbohydrates, fats, and proteins. • Exclusively synthesized by ___________ (found primarily in meat, eggs and dairy products). Vitamins Bacteria Image: VitaminB12 : NIH, Public Domain www.nlm.nih.gov/.../ency/imagepages/19516.htm

Two Types of Enzyme Inhibitors 1. ___________ ____________: Chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Competitive inhibition Substrate Competitive inhibitor

1. Competitive inhibitors: Resemble an enzyme’s normal substrate and compete with it for the active site. Image: Competitive Inhibition : www-biol.paisley.ac.uk/.../chapter3_2.html

Two Types of Enzyme Inhibitors _______________ ______________: Do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, altering the active site. Enzyme Noncompetative inhibition Noncompetitive Inhibitor Substrate active site altered

Enzyme Inhibitors Blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance. Many _____ are enzyme inhibitors. Enzyme inhibitors are also used as _________ and __________. Drugs Herbicides, pesticides Images Dead Bug : www.kansas.gov/help_center/user_testing.html Prescription Drugs : www.patentdocs.us/.../08/by-kevin-e-noon.html

Featured Enzyme #1: Catecholase Catecholase is present in most ______ and __________. It is the enzyme that facilitates the ________ of cut or bruised fruits and vegetables by catalyzing the following reaction: (______________) _________ + _____ ----------------- _____________ colorless substrate brown product Fruits, vegetables Browning Catechol + oxygen (catecholase) > polyphenol

Featured Enzyme #1: Catecholase & Noncompetetive Inhibition _________ juice and other acids are used to preserve color in fruit, particularly apples, by lowering the ____ and removing the copper site (cofactor) necessary for the enzyme to function. catecholase catechol + O2 -------------------------- polyphenol colorless substrate brown product Lemon pH

Featured enzyme #2: Bromelain Pineapple contains enzyme bromelain, which can _______ _________. Jell-O is made of gelatin, a processed version of a structural protein called _________ that is found in many animals, including humans. Collagen is a big, fibrous molecule which makes skin, bones, and tendons both strong and elastic. The gelatin you eat in Jell-O comes from the collagen in cow or pig bones, hooves, and connective tissues. (Yummie!) Examine 2 containers: a. In one, canned pineapple was used to make jello. b. The other, fresh pineapple was used. Digest protein collagen

LAB: Catalase Each enzyme is specific for the reaction it will catalyze. In this laboratory, Enzyme = catalase Substrate = hydrogen peroxide (H2O2) Products = water and oxygen H2O2 H2O + O2 If a small amount of catalase is added to hydrogen peroxide, you will be able to observe bubbles of ________________ forming.

Design of the Experiment In this experiment, you will investigate the rate at which the enzyme catalase converts substrate to product. You will allow catalase to react with hydrogen peroxide for varying amounts of time and then stop the reactions by adding H2SO4.To determine the amount of hydrogen peroxide that remains after the reaction, you will do a titration with KMnO4. In such a titration, you slowly add a chemical (KMnO4) that will cause a color change until a target color is achieved.

Titration To determine how much hydrogen peroxide (substrate) has been broken down by catalase at varying times, you measure the amount of peroxide remaining in each flask.

Reading the pipette Assume that the pipette is filled to the point indicated in the figure at the left. You would record the initial point as 3.30 ml; the ending point would be 3.90 ml. Therefore, the titration would have required 0.60 ml. Remember that you should read the number that is at the bottom of the meniscus.

We can calculate the rate of a reaction by measuring, over time, either the disappearance of substrate (as in our catalase example) or the appearance of product (as in the above graph). For example, on the graph above, what is the rate, in moles/second, over the interval from 0 to 10 seconds?

Analysis of Results so for this example, the rate would be