Urease spectroscopy

The composition, visible spectroscopy, and catalytic properties of urease have been reviewed by Blakeley and Zemer [25] and by Hausinger [2]. The urease from jack bean is typical of the enzymes from plants. It has a protein of relative... 

Hawtin, P.R., Delves, H.T. and Newell, D.G. (1991). The demostration of nickel in the urease of Helibacter pylori by atomic absorption spectroscopy. FEMS Microbiol. Lett., 77, 51. 

A for the two histidines. The other two Cu" ions are found in surface exposed sites coordinated by two histidine e nitrogens and one or two water molecules. The putative cysteine ligand identified by spectroscopy and mutagenesis " does not bind Cu" in the structure and is quite distant from the metal-binding sites. It may be that this interaction occurs in solution between a cysteine residue from one dimer and a Cu" ion from a second dimer, and is precluded in the structure by crystal packing. The dimer interface site is proposed to deliver Ni" ions one at a time to the urease active site, and the other two sites are proposed to play a more secondary role, serving as reservoirs for Ni". ... 

Optical spectral transformations of composite PESA films having a structure PAA(CTCT/PAA)n(Urease/PAA)ni were recorded by using UV-visible optical spectroscopy in order to study the reaction of urea decomposition. Typical UV/visible absorption spectra of these films are shown in Fig. 10. When the sample was soaked in urea solution, the band at 550 nm was found to be slightly shifted towards higher wavelengths with an additional band appeared at 440 nm. 

Enzyme/indicator optrodes for registration of enzyme reactions and their inhibitors, such as heavy metal ions and pesticides, can be produced by PESA technique. Composite films containing the enzyme urease and cyclo-tetra-chromotropylene as indicator molecules show some characteristic spectral transformations caused by urea decomposition. The reaction of inhibition of urease by heavy metal ions can be also registered with this method. Further development of the enzyme sensors and sensor arrays lies in finding suitable pairs of enzyme/indicator, their deposition by PESA method and studying the enzyme reactions (including inhibition) with UV-vis spectroscopy. 

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