Detection of alpha-urease dissociation by fluorescence emission spectroscopy.

alpha-Urease (E.C. 3.5.1.5) is a hexameric enzyme that can dissociate into two active trimers and further into six monomers (Hirai M., Kawa-Hirai, R., Hirai T., Ueki T. (1993) Eur. J. Biochem. 215, 55-61). We have attempted to detect these dissociation products using fluorescence emission and polarization spectroscopy. Our data suggest that the hexamer, the trimer and denatured monomer have fluorescence emission maximum at 330nm, 332nm, and 346nm, respectively, under our experimental conditions. We have also found that the conformation of urease subunits is only slightly modified upon dissociation to trimer, but drastically changed upon further dissociation leading to monomer.