3. Enzyme specificity. To determine the specificity of substrate binding for a particular enzyme/protein, structurally related compounds may be used as potential substrates and Km values may be calculated. However, many compounds structurally related to the substrate may bind to the active site but cannot be converted to product. In these instances, the substrate analogs are used as potential competitive inhibitors of substrate binding. Low K, values indicate high affinity of the enzyme for the inhibitor, whereas high K,values indicate low binding affinity. Consider the enzyme xanthine oxidase, which catalyzes the formation of uric acid from the purine bases hypoxanthine or xanthine in humans. The Km for hypoxanthine is 15.0 μM and for xanthine it is 45.0 μM. A few compounds used as competitive inhibitors of the normal substrate hypoxanthine are listed in the table below with their K, values. Comparing the structures of hypoxanthine with the listed substrate analogs, what can you conclude about the characteristics of molecules that this enzyme binds at its active site? OH hypoxanthine (Km = 15.0 μm) OH xanthine oxidase xanthine (Km = 45.0 μm) xanthine oxidase OH HO HO OH uric acid N- OH OH N OH uric acid Substrate analog Purine Adenine Guanine Allopurinol Inosine HO. HOH Structure 7N- N1 NH₂ OH OH OH "NH₂ K, (UM) 900 800 300 38 900
3. Enzyme specificity. To determine the specificity of substrate binding for a particular enzyme/protein, structurally related compounds may be used as potential substrates and Km values may be calculated. However, many compounds structurally related to the substrate may bind to the active site but cannot be converted to product. In these instances, the substrate analogs are used as potential competitive inhibitors of substrate binding. Low K, values indicate high affinity of the enzyme for the inhibitor, whereas high K,values indicate low binding affinity. Consider the enzyme xanthine oxidase, which catalyzes the formation of uric acid from the purine bases hypoxanthine or xanthine in humans. The Km for hypoxanthine is 15.0 μM and for xanthine it is 45.0 μM. A few compounds used as competitive inhibitors of the normal substrate hypoxanthine are listed in the table below with their K, values. Comparing the structures of hypoxanthine with the listed substrate analogs, what can you conclude about the characteristics of molecules that this enzyme binds at its active site? OH hypoxanthine (Km = 15.0 μm) OH xanthine oxidase xanthine (Km = 45.0 μm) xanthine oxidase OH HO HO OH uric acid N- OH OH N OH uric acid Substrate analog Purine Adenine Guanine Allopurinol Inosine HO. HOH Structure 7N- N1 NH₂ OH OH OH "NH₂ K, (UM) 900 800 300 38 900
Biology: The Dynamic Science (MindTap Course List)
4th Edition
ISBN:9781305389892
Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan
Chapter6: Energy, Enzymes, And Biological Reactions
Section: Chapter Questions
Problem 9TYK: Which of the following statements about inhibition is true? a. Allosteric inhibitors and allosteric...
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