Question

Foundations of Biological Sciences 1 Enzymes - 8 PART 4: THE EFFECT OF PH ON ENZYME ACTIVITY The pll scale measures the amount Another factor influencing the rate of enzyme catalysis is the pll of the of ons in a solution. The more solution. pH specifies the acidity or basicity of solution by measuring the the more acidic the solution and lower hydrogen ion consentation (H). Like temperature, pH affects the three- pH) dimensional shape of enzymes, thus regulating their function If pH 7, the solution is neutral If pH <7, the solution is acidic. 11 pll> 7. the solution is basic Enzymes generally have their pH optima corresponding to the environment in pH is based on a logarithmie wcale which they normally function. Some, like Pepsin (a hydrolytic enzyme in the Hache whole phe below 7 stomach), effectively operate at a very low pH (acidic). Others like alpha is 10x more acidic than the next amylase found in saliva, operate most effectively at a neutral pH. Still others. higher value like lipases, function best at basic pH values. As excy czyme has an optimal pll range, it can be assumed that outside that pl.range, the enzyme is inhibited. Er sxample, if the pH drops in the blood (called acidosis) then enzymes in the blood will be inhibited. If the pH climbs to an unacceptably high value (called alkalosis), then enzymes cease to function effectively. Normally, these conditions do not take place because of the highly efficient buffers found in the blood that restrict the pH of the blood to a very narrow range. Buffers are a substance or mixtures of substances that resist any change in the pH. There are many buffer systems found in the body to adjust the pH so that enzymes might continue to catalyze their reactions. In the following exercise, you will test the hypothesis that the reaction of the enzyme catechol oxidase is pll-dependent. You will test this by observing its reaction at different pH-levels. Review the above information, and formulare predictions to the hypothesis that catechol oxidase activity is pl- dependent. Predict what might happen to ente activity ander acidic, neutral and basic conditions, and why. Neural conditions Acidic conditions pH.Carly 7.is.considered as best ptt for catechol oxidase efficient activity whenptt.getsover ox. opproaches. Jess than... under these conditions locidic enzume have activity but not maximum, as pH offects the protein configuranan DHE IS.considered as nest.ph for...cotechol oxidase...so there. I nos.maximum enzymatic... activity..... Basic conditions. Under alkaline..condition... catechol oxidose nas less actity...for.catalysis, but not. Zero....30. jf. be! put enzyme activity ya pit, then this is the grom of catechol oxidase. Rmax activity ercuma activity

Answer 1

6 Series1 1 0 0 5 10 15 pH Hypothesis The reaction of enzyme catechol oxidase is pH dependent prediction - AT pH 7 it has optimum enzyme activity LC C LO un Color intensity

Foundations of Biological Sciences 1 Enzymes -9 Procedure With a china marker, label seven test tubes with your initials, and pH2, pH4-PH12. 1. 2. Take the tubes to the location of the phosphate buffer series and fill each tube with 2 ml of the corresponding buffer (e.g. fill the tube marked pH 2 with 2 ml of the buffer marked pH 2 etc.). Use the graduated cylinders to add the buffers. 4. Return to your work area and add I ml ofpotato extract to each of the seven tubes. Agitate the tubes by hand. Table 4: Effect of pH on Enzyme Activity Color Intensity Add 1 ml of 1% catechol to each of the seven tubes. Cap the tubes and mix contents. 5. pH 2 pH 4 pH 6 pH 7 pH 8 ч 6. Place the tubes in the 40°C water bath. Mix the tubes periodically over the next 10 min. pH 10 pH 12 After 10 min. remove the tubes from the water bath and record the color intensity of each tube's content in table 4. 7. 1) Over what pH range does catechol oxidase catalyze catechol to benzoquinone? Catechol oxidase is more the histidine residues to the catalytic copper centers. catalytically active in the pH 4-8 range due to coardination of 7 2) What is the optimum pH for catechol oxidase activity?. Homework: Based on data summarized in Table 4, make a graph expressing the activity of catechol oxidase as a function of variation in pH. Remember to write a figure caption and your hypothesis/prediction with the graph.