(a)[2]
Draw the structure of the dipeptide, ser-lys, with molecular formula $\mathrm{C_9H_{19}N_3O_4}$. The peptide functional group that is formed should be shown.
(b(i))[1]
State what is meant by isoelectric point.
(b(ii))[3]
A mixture containing serine, lysine and ser-lys is examined by electrophoresis in a buffer at $\mathrm{pH\ 5.7}$. Draw and label three spots on Fig. 9.2 to show where each of the three species, serine, lysine and ser-lys, is expected to be after electrophoresis. Explain your answer.
(c(i))[1]
Fig. 9.3 shows the preparation of compound $R$ from compound $P$. Draw the structure of $Q$ in Fig. 9.3.
(c(ii))[2]
State the reagents and conditions for steps 1 and 2 in Fig. 9.3. step 1 step 2