The nickel ion environment in jack bean urease.

Area of Science:

• Biochemistry
• Biophysics
• Inorganic Chemistry

Background:

• Jack bean urease is a nickel-containing metalloenzyme.
• Previous studies suggested similarities between the nickel ion environment in urease and model compounds.

Purpose of the Study:

• To perform a detailed extended X-ray absorption fine structure (EXAFS) analysis of jack bean urease.
• To solve the crystal structures of two nickel-containing model compounds.
• To compare the nickel ion environment in urease with that in the model compounds.

Main Methods:

• Extended X-ray absorption fine structure (EXAFS) spectroscopy.
• X-ray absorption near edge structure (XANES) spectroscopy.
• X-ray crystallography.

Main Results:

• The nickel ion environment in jack bean urease shows the closest similarity to the model compound Ni(L)2(L')1(ClO4)1.
• Detailed EXAFS analysis confirmed structural similarities.
• Crystal structures of Ni(L)2(L')1(ClO4)1 and Ni(HMB)3(Br)2 were determined.

Conclusions:

• The nickel ion in jack bean urease is coordinated in a manner similar to that in the Ni(L)2(L')1(ClO4)1 model compound.
• This detailed structural information aids in understanding urease's catalytic mechanism.