Structure, Equilibrium and Ribonuclease Activity of Copper(II) and Zinc(II) Complexes Formed with a Dinucleating Bis-Imidazole Ligand

Nucleophilic reaction by carbonic anhydrase model zinc compound: characterization of intermediates for CO2 hydration and phosphoester hydrolysis

“…The observed sigmoidal pH dependence of k 2 was similar to a number of phosphoester hydrolyses promoted by many different zinc model compounds [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63]; the inflection point (pH 8.6) of a sigmoidal curve was close to the determined pK a ¼ 8:4 by pH titration method.…”

Unsymmetrical dizinc complexes as models for the active sites of phosphohydrolases

“…7(a), formation of H 4 L only occurs at very low pH and all basic positions are not protonated within the pH range of this study. 43 In the case of bimido, it was found that only a mononuclear complex was stable between pH 4.5-7 in the presence of two equivalents of zinc; this observation could be explained by a crystal structure of this species, revealing a non-coordinated alcohol group and coordination of the single zinc ion by all the other groups in the ligand. The next two deprotonation steps are likely to occur at the two ammonium groups; the large difference between these two pK a values may be due to different degrees of hydrogen bonding to nearby functional groups.…”

Zinc(II) tweezers containing artificial peptides mimicking the active site of phosphotriesterase: The catalyzed hydrolysis of the toxic organophosphate parathion

“…These metal ions, and/or the water bound to them, cooperate and as a result, hydrolyze stable phosphoesters under physiological conditions [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The presence of two or three zinc(II) centers in a single complex appears to be important for activation and recognition of cleavage sites within phosphate esters [24][25][26][27][28]. Moreover, these complexes generate highly cationic species that favor the electrostatic attraction to the phosphate backbone.…”