4. and 5. please . Specialized transporter proteins are needed to allow ions to cross biological membranes. These

transporters typically feature a narrow channel, called the "selectivity filter," that selects for specific ions

while excluding others. The potassium channel, for example, selects specifically for K* ions while excluding

ions that are either larger or smaller than K*.

4. Specialized transporter proteins are needed to allow ions to cross biological membranes. These transporters typically feature a narrow channel, called the "selectivity filter," that selects for specific ions while excluding others. The potassium channel, for example, selects specifically for K ions while excluding fons that are either larger or smaller than K. a. The potassium channel uses a strategy similar to the editing site of isoleucyl-aminoacyl tRNA synthetase to exclude ions that are larger than K. Based on this, briefly explain how an ion like Rb would be excluded from the potassium channel. b. As lons pass through the potassium channel, they become desolvated and form ion-dipole interactions with carbonyl groups in the protein channel. Based on the diagram below, explain in terms of enthalpy how this desolvation process allows the potassium channel to exclude smaller ions like Nat. HH H I I OK...10 1 NA 10 T 0.(K). Fo 10 I HH H solvated ions ions in selectivity filter [Continued on the next page.] 5. Sulfanilamide, shown below, was one of the first antibiotics to be used widely in the treatment of bacterial infections. This specific antibiotic functions by binding to the active site of an enzyme involved in the production of vitamin B, and preventing the substrate from binding. NH2 0:6=0 H2N Sulfanilamide A computer model of sulfanilamide in the enzyme active site is below. Several variations of sulfanilamide are shown below. Which of the following molecule would bind best to this active site? Briefly explain your answer. NH2 NH2 monitor HAN HEN 2 3 (Continued on the next page.]