Enzymes Proteins that act as biological catalysts Proteins that act as biological catalysts Substrates are molecules that an enzyme binds during a particular reaction Substrates are molecules that an enzyme binds during a particular reaction Catalysts- molecules that increase the rate of a reaction without being used up in the reaction Catalysts- molecules that increase the rate of a reaction without being used up in the reaction Enzymes are proteins so all the general properties of proteins apply to enzymes Enzymes are proteins so all the general properties of proteins apply to enzymes

Enzymes (cont’d) Structure Structure –Primary Structure- determined by amino acids –Secondary Structure- β-sheets and α-helices –Tertiary Structure- composed of elements of secondary structure  Hydrogen bonding, Hydrophobic interactions, Ionic bonding and Covalent bonding –Quaternary Structure- composed of multiple polypeptide chains

Enzymes (cont’d) Enzymes promote particular reactions Enzymes promote particular reactions –Determined by its three dimensional structure –Specific substrate binding Enzyme binds to substrate via the active site Enzyme binds to substrate via the active site –Active site has specific shape and chemical properties that allow it to promote a specific reaction

Enzymes (cont’d) Factors that effect enzymes Factors that effect enzymes –pH and temperature- variations can lead to altering of tertiary structure making it inactive; Most of the time is a permanent change –Organic Solvents- disrupt hydrophobic bonds (involved in tertiary and quaternary structure); Reversible –Inhibitors- Prevent enzyme from binding to substrate –Protease- breaks down enzyme

Lab Info Work in groups of 4 Work in groups of 4 Only 1 person in each group will handle the sodium azide Only 1 person in each group will handle the sodium azide –Wear goggles and gloves Use the same hydrogen peroxide for every reaction EXCEPT after the sodium azide Use the same hydrogen peroxide for every reaction EXCEPT after the sodium azide –Dispose of hydrogen peroxide in waste container Only have to do the control once Only have to do the control once –But make sure to include it on every graph Label tube that will go in the incubator clearly Label tube that will go in the incubator clearly

Lab Info Handle filter paper discs with tweezers Handle filter paper discs with tweezers –Oil from your skin will alter reaction Start timing as soon as the disk is in the hydrogen peroxide and stop timing as soon as it reaches the top Start timing as soon as the disk is in the hydrogen peroxide and stop timing as soon as it reaches the top –Measure time to nearest 0.1 second If the disk does not rise after 3 minutes assume no reaction will occur If the disk does not rise after 3 minutes assume no reaction will occur

Lab Report Must be TYPED Must be TYPED Should have 5 graphs (Bar Graphs) Should have 5 graphs (Bar Graphs) –Graph the reciprocal time 1/T (Rate of the reaction) –Graph the average of the runs of each experiment –Put error bars on the graphs –Graphs should contain a clear legend  States method of measurement and identifies points and error bars –Look in lab manual for an example

Example of Data Table For Lab Report Trial 1 Trial 2 Trial 3 Averag e Standard Deviation DeviationStandardError Control Concentration 1 Concentration 2 Concentration 3

Assignments All lab reports must be typed All lab reports must be typed Do the lab report as follows- differs from lab manual Do the lab report as follows- differs from lab manual –Intro: Short background about the lab; include hypothesis –Materials and Methods: Summarize briefly; don’t need exacts –Results: tables/graphs of data and text to summarize what they show –Discussion: analysis of results; troubleshoot lab if it didn’t work –Conclusion: short summary of everything All assignments are due at the beginning of the next lab. All assignments are due at the beginning of the next lab.

Order of Experiment 1. Start Trypsin reaction 2. Run Control disc 3. Effect of concentration –Run [100%], [50%], [25%] 3 times each 4. Effect of temperature –Run boiled, room temperature, and iced samples 3 times each 4. Effect of pH –Run pH 3, 5, 7, 9 three times each 4. Effect of Proteases –Run Trypsin sample 3 times each (must incubate ~1 hour) 5. Effect of Inhibitor –Run Sodium Azide sample 3 times each. –Dispose of h202 in waste container.