Electrostatic and Hydrophobic on Recognition and Deacylation of an Anionic Ester by Ni(￥±)-Macrocyclic Complexes Built on Poly(ethylenimine)

摘要

Three derivatives of poly(ethylenimine) (PEI) are prepared by Ni(ケ)-template condensation with glyoxal(GO): PEI[Ni(ケ)-GO]0.08 (1), PEI[Ni(ケ )-GO]0.03 (2), and lau0.18PEI[Ni(ケ)-GO]0.03 (3). The contents of Ni(ケ)-macrocyclic center of 1-3 are 8%, 3%, or 3%, respectively, of the monomer residues, and 18% of monomer residues for 3 are laurylated. The pH profiles for kcat and km for the deacylation of 4-carboxy-2-nitrophenyl acetate are measured. The relative magnitude of the parameters for 1-3 and different shapes of the pH profiles for 1-3 are explained in terms of the electrostatic and the hydrophobic effects exerted by the metal centers and lauryl groups. For the artificial metalloenzymes built on PEI, therefore, the ionization of functional groups and the affinity toward counter-anions can be controlled by adjusting charge density and the content of hydrophobic groups.