1. Find the structure of prion from PBD. (A) List the following information :
(1)ID number, (2) Authors, (3) the number of residues in one monomer, (4) the number of disulfide bonds.

(B) Put the structure of prionon your homepages. Show different color for different secondary structurein cartoon form with sideshains on (helix in blue, sheets in red).Show the script that makes the final picture.

2. Transcription of the ant gene during lytic growth of bacteriophage P22 is regulated by the cooperative binding of two Arc repressor dimers to a 21-base-pair operator site. Please find the co-crystal structure of this Arc tetramer-operator complex from PDB.

(a) Show the DNA sequences of the Arc operator.

(b) The picture below is the hydrogen bonds between beta-sheet side chains and DNA bases. Show three side chains (gln9, asn11, arg13) from one monomer and corresponding DNA bases of them on your home page. Color three side chain with different color. Measure the distance between possible hydrogen bonds (at least three).