MEDizzy - A 64-year-old man complains of an acute onset of unilateral

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Enzymes and Biochemistry of Digestion

A 64-year-old man complains of an acute onset of unilateral eye pain and a reduction in visual acuity. On physical examination, you notice conjunctival injection (eye redness) and a mid-dilated and nonreactive pupil. Funduscopic examination reveals cupping of the optic disc. Recognizing the signs and symptoms of glaucoma, you administer the medication acetazolamide to decrease the production of aqueous fluid and lower the intraocular pressure. Acetazolamide is a noncompetitive inhibitor of carbonic anhydrase and, therefore, will lead to which of the following concerning the kinetic constants of carbonic anhydrase?

ExplanationA noncompetitive inhibitor binds to the enzyme at a site different than where the substrate binds. Therefore, the number of enzymes capable of catalyzing the reaction is decreased, resulting in a decrease in Vmax. Because the inhibitor binds at a site distinct from that of the substrate, increasing the substrate concentration cannot overcome the effect of the inhibitor. Consequently, Km remains unchanged, and the inhibitor does not interfere with substrate binding