THE CATALYTIC ACTION OF ZN-2+-METALLOENZYMES REQUIRES A PENTA-COORDINATE METAL-OH2 COMPLEX uri icon

abstract

  • A review is presented of the spectroscopic and chemical evidence that the tetra-coordinate active site metal ion of carboxypeptidase A and liver alcohol dehydrogenase accommodates both the substrate and a water molecule in catalytically competent reaction intermediates to form a penta-coordinate complex. In carboxypeptidase A ionization of the metal-OH2 complex forms a potent metal-hydroxide nucleophile for breakdown of the acylenzyme (mixed anhydride) reaction intermediate in esterolysis, while in liver alcohol dehydrogenase a neutral metal-OH2 species serves as a conduit for proton abstraction from the alcoholic hydroxyl group. These results together with correlated observations that the catalytic activity of other Zn2+-metallo-enzymes depends on ionization of a Zn2+-OH2 complex suggests that a penta-coordinate metal-OH2 species is an obligatory species in the catalytic action of this class of enzymes. 1984.

published proceedings

  • JOURNAL OF MOLECULAR CATALYSIS

author list (cited authors)

  • MAKINEN, M. W., KUO, L. C., YIM, M. B., MARET, W., & WELLS, G. B.

citation count

  • 6

complete list of authors

  • MAKINEN, MW||KUO, LC||YIM, MB||MARET, W||WELLS, GB

publication date

  • March 1984