Figure 1.

Purification of commercial urease type IX (Sigma-Aldrich) and characterization of postpurification products. (A) Scheme of the purification of urease as received (Ur-AR) by size-exclusion chromatography (SEC) and analysis of urease by SDS-PAGE before purification, as well as the SEC fractions (postpurification). (B) Reducing SDS-PAGE gel showing the protein composition of Ur-AR. (C) SEC chromatograms of the Ur-AR purification (with major peaks highlighted in blue, purple, and orange) and gel filtration protein standards (670 and 158 kDa protein peaks correspond to thyroglobulin and bovine γ-globulin, respectively). (D) Reducing SDS-PAGE gel showing the fractions corresponding to the three major SEC peaks found in C. (E) Michaelis–Menten fits of the recorded reaction rates for urease activity from the fractions corresponding to SEC peaks P1, P2, and P3. (F, G) Characterization by dynamic light scattering of urease samples before (F) and after (G) purification.