Carbonic anhydrase models. 4. [Tris[(4,5-dimethyl-2-imidazolyl)methyl]phosphine oxide]cobalt(2+), a small-molecule mimic of the spectroscopic properties of cobalt(II) carbonic anhydrase

Abstract

The title compound when bound to Zn(II) or Co(II) displays many properties in common with carbonic anhydrase. These include a weak ability of the Zn(II) complex to catalyze the interconversion of C02 and HC03~a nd anion-dependent visible absorption spectra of the Co(II) complex. Titration data indicate both the Zn(II) and Co(II) complexes labilize an additional group associated with the complex which appears to be M+-OH2. In the presence of anions, the spectrophotometric pK" for the Co(II) complex shifts to higher values as it does in Co(II)CA. An explanation for the anion-dependent properties of CA is offered on the basis of the observations with this small-molecule complex.

A mononuclear cobalt(II) hydroxo complex: synthesis, molecular structure, and reactivity studies

“…Attempts to mimic the metal coordination environment in carbonic anhydrase and other zinc-containing enzymes were met with limited success [12][13][14] before the first report of LZnOH, where L = KHB (3-The structurally characterized mononuclear hydroxo complexes with pyrazolylborate are limited in the literature. Hikichi et al reported the crystal structure of mononuclear iron hydroxide in 1997 [17], whereas Fujisawa and co-workers reported the crystal structure of mononuclear copper hydroxide having pyrazolylborate as supporting ligand [18].…”

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

“…In a number of the reported studies on the zinc model compounds as the active center of CA , most of them consist of pyrazolylborate ligands [10][11][12][13][14][15][16][17][18][19] or macrocyclic amine ligands [20][21][22][23][24][25][26], a few of zinc model compounds are the structural and functional CA model having histidine-arising imidazoles [27][28][29][30][31][32][33][34][35][36] inherent as the CA active center [1][2][3][4][5][6][7][8][9]. For zinc compounds with imidazolylphosphine ligands, their syntheses and structures [27][28][29], and kinetic studies on CO 2 hydration are reported [30][31][32][33].…”

“…The zinc complex with L1s 3À [36,37] could be studied on the CO 2 hydration kinetics in water. The water-soluble zinc compound [L1sZn(OH 2 )] À showed the largest rate constant [36] among the CA model compounds reported so far [20,23,24,[31][32][33].…”

Zweikernige Palladium(II)-, Platin(II)- und Iridium(III)-Komplexe von Bis[imidazol-4-yl]alkanen

“…Zwei Imidazolringe ko È nnen in einfacher Weise u È ber eine aliphatische (CH 2 ) n oder eine aromatische Bru È kke an den Positionen [6], Fe II [6], Ni II [7], Co II [8], Mo0 [9], Rh, Ru [10] und Ir [11]. Bisimidazol-Komplexe von Pt II [5 a] und Cu II [12] zeigten cytostatische Wirkung.…”