(Solved): Proliferating Cell Nuclear Antigen (PCNA) is a ring-shaped protein that forms a clamp around DNA. ...

Proliferating Cell Nuclear Antigen (PCNA) is a ring-shaped protein that forms a clamp around DNA. DNA polymerase binds to the outside of the PCNA clamp, keeping the polymerase tightly associated with DNA during replication. PCNA is a homo-oligomer; each subunit is shown as a different color in the image below. 6 a. In the lab, you purify PCNA from mouse tissue. Based on the protein sequence, the extinction coefficient for a single PCNA molecule at \( 280 \mathrm{~nm} \) is \( \varepsilon= \) \( 15,930 \mathrm{M}^{-1} \mathrm{~cm}^{-1} \). What is the extinction coefficient for the homo-oligomeric PCNA clamp? b. Your purified sample of murine PCNA absorbs \( 72 \% \) of incident light at \( 280 \mathrm{~nm} \) using a standard \( 1 \mathrm{~cm} \) path length cuvette. What is the concentration in micromolar?