Magnetic and optical properties of copper-substituted alcohol dehydrogenase: a bisthiolate copper (II) complex.

Replacement of the catalytic Zn(II) in horse liver alcohol dehydrogenase (HLADH) with copper produces a mononuclear Cu(II) chromophore with a ligand set consisting of two cysteine sulphurs, one histidine nitrogen plus one further atom. The fourth ligand to the metal ion and the conformation of the protein may be altered by addition of exogenous ligands and/or the cofactor NADH. Absorbance, CD, low-temperature magnetic CD (MCD) and EPR spectra are presented of copper-substituted HLADH samples in both 'open' and 'closed' conformations and in the presence and absence of the exogenous ligands pyrazole and DMSO.

Cd-substituted horse liver alcohol dehydrogenase: catalytic site metal coordination geometry and protein conformation.

The coordination geometry of the catalytic site in Cd-substituted horse liver alcohol dehydrogenase (LADH) has been investigated as a function of pH using the method of perturbed angular correlation of gamma-rays (PAC). LADH in solution fully loaded with cadmium, including radioactive 111mCd in the catalytic site [Cd2(111mCd)Cd2LADH], was studied over the pH range 7.9-11.

Copper(II)-substituted horse liver alcohol dehydrogenase: structure of the minor species.

Oxygen treatment of horse liver alcohol dehydrogenase EE isozyme substituted with Cu(II) at the catalytic site leads to bleaching with concomitant reduction to Cu(I) of approximately 90% of total Cu(II). The Cu(II) of the remaining 'minor species' cannot be reduced nor does it interact with exogenous ligands, e.g.

Coordination geometry for cadmium in the catalytic zinc site of horse liver alcohol dehydrogenase: studies by PAC spectroscopy.

Active site substituted Cd(II) horse liver alcohol dehydrogenase has been studied by Perturbed Angular Correlation of Gamma rays Spectroscopy during turnover conditions for benzaldehyde and 4-trans-(N,N-dimethylamino)cinnamaldehyde. The ternary complex between alcohol dehydrogenase NAD+ and Cl-, and the binary complex between alcohol dehydrogenase and orthophenanthroline have also been studied. The Nuclear Quadrupole Interaction parameters have been interpreted in terms of different coordination geometries for Cd(II) in the catalytic zinc site of the enzyme.