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Enzymes

Enzymes. Proteins that act as biological catalysts 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

wilma-bonner
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Enzymes

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  1. Enzymes • Proteins that act as biological catalysts • 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 • Enzymes are proteins so all the general properties of proteins apply to enzymes

  2. Enzymes (cont’d) • 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

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

  4. Enzymes (cont’d) • 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

  5. Lab Info • Work in groups of 4 • 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 • Dispose of hydrogen peroxide in waste container • 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

  6. Lab Info • 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 • Measure time to nearest 0.1 second • If the disk does not rise after 3 minutes assume no reaction will occur

  7. Lab Report • Must be TYPED • 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

  8. Example of Data Table For Lab Report

  9. Assignments • All lab reports must be typed • 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.

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

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