GCN4 is one of the best known coiledcoil proteins with a par

GCN4 is one of the best known coiled-coil proteins, with a partial sequence: LEDKVEELLSKNYHLENEVAARLKKEVGE Draw a valid helical wheel diagram for this sequence. We will accept any valid helical wheel diagram, but the simplest is the one shown in class (with each subequent heptad going \"out\" a ring, as Dr. Ottesen showed on the board). Circle the portion of the helical wheel diagram that you would expect to correspond to a potential coiled-coil interface. Coiled-coils are sometimes thought of as \"molecular rulers\" because of their rigidity. Given what you know about the properties of a-helices, what distance (in A) would you expect this 28-residue coiled-coil region to extend? Show your math. Draw a Ramachandran Plot and label your axes. Mark with an X the region of the plot where residues in the alpha -helix above would likely be found. What are the values of the psi and phi angles of the amino acid residue in the structure shown here?

Solution

Answer:

3) The and angles of the amino acid residue in the structure have no specific double bond character and hence they rotate at any angle with respect to one another. Also the backbone and side-chains atoms limit the allowed and angles to a very small range.