ENZYME ACTION – MEASURING RATE OF REACTION – SUBSTRATE CONCENTRATION The effects of the following factors on the rate of enzyme controlled reactions – enzyme concentration, substrate concentration, concentration of competitive and of noncompetitive inhibitors, pH and temperature.

Do now: Exam Question Explain the current model of enzyme action and outline how have models of enzyme action developed. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model.

Activation energy  Chemical reactions require a certain amount of energy to start.  This is called the Activation energy.  Enzymes lower the activation energy needed for a reaction to happen. This means that a reaction can happen with less energy input and so reactions will happen quicker.  We call them biological catalysts Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model.

How to measure reaction speed?  How could you measure the progress of a reaction?  Record the dependent variable  How could you measure how fast a reaction is happening?  Record the dependent variable every-time you change the independent variable. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model. How could you measure the rate of reaction for these enzyme controlled reactions: 1)A reaction that breaks down water into Hydrogen and oxygen gases 2)A reaction that produces heat the more products made. 3) A reaction that makes products that change colour.

Effect of enzyme concentration on rate of reaction  What is the relationship shown in the graph?  Link back to active sites? Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model.

In which of these will the rate of reaction be fastest?  Why would not adding anymore substrate make the reaction faster? Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model.

Enzyme controlled reactions - substrate concentration Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how enzymes catalyse reactions by lowering activation energy -Outline a method for measuring enzyme action in a reaction. -Analyse results from the substrate rate graph and explain conclusions linking back to the enzyme substrate model.

ENZYME ACTION – MEASURING RATE OF REACTION – TEMPERATURE AND PH The effects of the following factors on the rate of enzyme controlled reactions – enzyme concentration, substrate concentration, concentration of competitive and of noncompetitive inhibitors, pH and temperature.

Do now: Enzyme rates and temperature  Look at this enzyme rate graph. Explain the different phases of each part. Link this back to GCSE knowledge and A-level knowledge Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Describe the term denaturing relating back to active site and enzyme substrate complexes. -Analyse results from the rate graph and explain conclusions linking back to the protein structure and the enzyme-substrate model.

Effect of temperature on rate of reaction.  Most enzyme controlled reactions require an optimum temperature of 37 degrees celsius.  If lower than this….. And so the rate of these reactions is slower.  If higher than this…. And so the rate of these reactions are slower. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Describe the term denaturing relating back to active site and enzyme substrate complexes. -Analyse results from the rate graph and explain conclusions linking back to the protein structure and the enzyme-substrate model.

Denaturing of Enzymes  Why is the shape of the enzyme so important to its function?  The substrate has a complimentary shape that fits exactly into the enzyme so the reaction can happen.  What determines the enzymes/proteins specific shape?  The primary, secondary, tertiary and quaternary structures.  What would happen if the shape of the enzyme changed? Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Describe the term denaturing relating back to active site and enzyme substrate complexes. -Analyse results from the rate graph and explain conclusions linking back to the protein structure and the enzyme-substrate model.

Denaturing of Enzymes  Denaturisation – when the enzymes active site changes shape and deforms.  The substrate is no longer complimentary  The complex cannot form and the reaction cannot happen  Why does rate of reaction not just drop to zero after 37 degrees? Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Describe the term denaturing relating back to active site and enzyme substrate complexes. -Analyse results from the rate graph and explain conclusions linking back to the protein structure and the enzyme-substrate model.

pH and rates of reaction Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Describe the relationships between temperature and rate of reaction and pH. -Describe the term denaturing relating back to active site and enzyme substrate complexes. -Analyse results from the rate graph and explain conclusions linking back to the protein structure and the enzyme-substrate model.  Acids contain high amounts of H+ ions  Alkalis have high amounts of OH- ions  These can interfere with the structure of the active site and denature the enzymes

ENZYME ACTION - INHIBITORS The effects of the following factors on the rate of enzyme controlled reactions – enzyme concentration, substrate concentration, concentration of competitive and of noncompetitive inhibitors, pH and temperature.

Do now:  Long answer question: Explain the importance of protein structure in enzyme function and how different factors can affect this. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms. Mini – Practical: 1) Add the catalase to the hydrogen peroxide, measure how much oxygen is produced in a minute. 2) To the catalase, add 20mls of copper sulphate solution, leave for 3 minutes. Now add the hydrogen peroxide and measure in a minute.

Inhibitors Chemicals that bind to an enzyme and reduce its activity.  Competitive Inhibitors  Bind to the active site just like a substrate would  Non competitive inhibitors.  Bind to the allosteric site permanantly and denature the active site. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.

Competitive Inhibitors  Have a complimentary shape just like a substrate.  ‘compete’ with the substrate to bind with the enzyme.  When substrate concentration increases, the inhibitors are less effective. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.

Competitive Inhibitors  Vmax value is the same for normal enzyme and an enzyme inhibited competitively. Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.

Non- Competitive Inhibitors Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.  The inhibitors bind at the allosteric site, not the active site!  They cause the shape of the active site to change (denature)  Substrates cant bind anymore, no matter how much substrate you add.

Non- Competitive Inhibitors Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.  The vmax is half of what a normal enzyme reaction would be.

Negative feedback of Enzyme Inhibition  What does negative feedback mean?  The products of an enzyme reaction feedback and act as inhibitors for the enzyme to stop too much reaction happening  In what process do you think this is important? Outcomes: -Recall enzyme structure and the mechanism of the enzyme substrate complex. -Explain how competitive inhibitors decrease enzyme action linking to terms active site and complementary shape. -Explain how non- competitive inhibition reduces enzyme action by attachment to allosteric site. -Apply knowledge of inhibition to explain some negative feedback mechanisms.