Open AccessInert Chromium and Cobalt Complexes as Probes of Magnesium‐Dependent Enzymes
Author(s) -
Black Christopher B.,
Cowan James A.
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00684.x
Subject(s) - catalysis , chemistry , chromium , cobalt , coordination sphere , metal , transition metal , exonuclease iii , metal ions in aqueous solution , inorganic chemistry , escherichia coli , organic chemistry , biochemistry , gene
An investigation of the metal ion dependence of Escherichia coli exonuclease III, 3'‐5'‐exonuclease and exoribonuclease H activities is reported. Catalytic activation of E. coli exonuclease III has been examined for a series of inert chromium complexes Cr(NH 3 ) 6‐x (H 2 O) 3+ x (x = 0–6) that bear water and ammine ligands in well defined inner‐sphere geometries. The importance of hydrogen bonding and electrostatic stabilization for catalysis of this reaction were quantitatively evaluated. Catalytic activation by the essential metal cofactor appears to be mediated through transition‐state stabilization by outer‐sphere complex formation with substrate. Hydrogen bonding to metal‐bound water molecules is the dominant stabilizing interaction.