You are told that the structure of a channel that allows protons to cross the bacterial membrane has 12 amphipathic α -helices.
a. Describe the orientation of these helices with respect to the plane of the membrane. The 12 Helices will be oriented.
b. Describe how both the polar sidechains and the nonpolar sidechains within the helices are arranged within the protein structure.
c. The function of this protein is to move protons through a water-filled cavity between the 12 helices. Which two of the following amino acid side chains would be most likely to line this water-filled channel? (Circle the correct ones). Ser Gln Met Trp
d. If the pH of the cell cytoplasm is 8.0 and the pH of the extracellular medium is 6.5, what do you expect the thermodynamically favorable direction of proton transfer to be?