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Transcript
ENZYMES Enzymes help with most chemical reactions in the body Digestion requires Enzymes • Amylase in salivary glands • Pepsin in stomach • Lipase and trypsin in small intestine Enzyme supplements • Aid in digestion Enzymes assist in 2 main types of reactions in cells 1) Synthesis = Synthesize (make) compounds A + B AB 2) Decomposition = Decompose (break) compounds CD C + D These reactions require energy Activation energy • Energy required for a chemical reaction to occur Most chemical reactions in cells occur too slowly for life to survive Catalyst • An inorganic chemical that lowers the activation energy so a reaction can occur Enzymes • Natural organic catalysts made of protein that lower the activation energy so a reaction can occur fast enough for cell to survive Enzymes are very complex proteins • Proteins are three dimensional The shape of a protein determines its function Four levels of structure • Primary structure – sequence of amino acids • Secondary structure – alpha helix, beta pleated sheets • Tertiary structure – Hydrogen bonds hydrophobic interactions, ionic bonds • Quaternary structure – 2 or more poly peptides together Primary structure H bonds form secondary structure forms with peptide bonds Tertiary structure forms from other bonds Enzyme key Terms • Enzyme – The protein that catalyzes a reaction • Substrate - The molecule that the enzyme attaches to • Active site - The spot on the enzyme that fits into the substrate Substrates fit into enzymes Enzyme helps reaction occur so substrate(s) forms the product Enzymes and substrates have a specific fit • Like a lock and key Induced fit • When active site adjusts to fit substrate Induced Fit and Hexokinase Synthesis using enzyme • A + B + Enzyme = AB + Enzyme Decomposition using enzyme • CD + Enzyme = C + D + Enzyme Enzymes are not used up!!! • Enzymes are on both sides of equation • Enzymes can keep working! Unless denatured • Heat, acid etc. can denature enzymes Denaturing enzyme • Heat etc. will break bonds of protein tertiary structure. Reversible • Primary structure can stay intact Enzyme animation • Claymation enzyme 30 secs • http://www.youtube.com/watch?v=ybahzSj UpB0&feature=related • Pacman Animation 2 mins • http://www.youtube.com/watch?v=CZD5xs OKres Enzymes in industry • Rennin used to manufacture cheese, Paper industry • Enzymes remove lignin to soften paper. Contact lenses • Proteases clean lenses of protein The enzyme catalase • Peroxide kills cells • cells have catalase to protect against peroxide • Catalase breaks peroxide into water and oxygen gas • H2O2 + Enzyme H20 + O2 + Enzyme Enzyme Regulation • • • • Temperature pH Concentration of enzyme or substrate Inhibitors Every enzyme has an optimal temperature Effect of TEMPERATURE • Increased temperature increases particle motion and enzyme reaction rate. BUT Enzymes are proteins and above a certain temperature they denature Effects of pH • Changes in pH also denature enzyme • Change in pH can alter the active site and keep substrate from binding Enzymes have an optimal pH • Pepsin in stomach - acid • Trypsin in intestine - base Competitive inhibitor • Blocks active site from substrate Non Competitive inhibitor • Attaches to enzyme in different place and alters its active site Toxic substances are often enzyme inhibitors • They stop important biological processes • Ex cyanide, lead, mercury, pesticides Allosteric enzymes • • • Enzymes that can be altered by an noncompetitive inhibitor A reaction product can act as a feedback inhibitor to slow enzyme. These can also be Promoters! That increase enzyme activity Animations of enzymes • http://www.kscience.co.uk/animations/ani m_2.htm