question about enzyme reaction rate 4a. What was the optimum pH of catalase? Not
ID: 198816 • Letter: Q
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question about enzyme reaction rate
4a. What was the optimum pH of catalase? Note that at other pH's (except for pH-3) the reaction rates were lower than those at the optimal pH, but that the enzyme clearly was still intact, as the H202 was still converted into H20 and 02. Explain the mechanism(s) of how nonoptimal pH's cause enzymes to have lower reaction rates. 4. 4b. Some enzymes are highly resistant to pH changes-i.e., their reaction rates do not change much when pH is changed. Refer to your answer to the 4a and propose structural characteristics that might make enzymes pH resistantExplanation / Answer
4a. Catalase is an enzyme that breaks down hydrogen peroxide H2O2 into water and oxygen. Its optimum pH is 7. At its optimum pH , the conformational shape of enzymes is such that all the active sites fit perfectly with the substrate. When the pH decreases (or increases), there is disruption of some hydrogen bonds between lops of the protein chains. If such disruptions occur near the active site of the enzyme, the active site will be distorted. Hence, the enzyme does not fit perfectly in the active site. Hence, not all substrate will be converted to product. Few enzymes will form an enzyme substrate complex. Hence, reaction rates will decrease.
4b. The enzymes that have are pH resistant usually have their active sites buried deep within the protein. These active sites are mostly hydrophobic region and hence, are inaccessible to H+/OH- ions present in the solution. These enzymes have rigid structure and cannot be disrupted. The inaccessibility of active site, protects them from the changes in pH. They are also resistant to proteolysis.
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