Thymidylate synthase (TS) is critical in the early stages of DNA biosynthesis. Thymidylate synthase (show below) possesses three critical amino acid residues: Cys 198, Arg 218, and Glu 60. What are the critical interactions shown for each amino acid shown below. Propose mutations that would not result in a loss of activity for each critical amino acid.

E-Glu60- OH deoxyR HN E-Cys198 E-Glu60- NH NH E-Arg218 deoxyR wwwwwwwww S E-Cys198 IZ + MTF CH2 NHR Thymidine