- Substitution of a serine residue for proline-87 reduces catalytic activity and increases susceptibility to proteolysis of Escherichia coli adenylate kinase. Gilles, A.M., Saint-Girons, I., Monnot, M., Fermandjian, S., Michelson, S., Bârzu, O. Proc. Natl. Acad. Sci. U.S.A. (1986)