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Biophys Chem. 2004 Sep 1;111(1):79-87.

Jack bean urease (EC aggregation monitored by dynamic and static light scattering.

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Department of Biophysics, IB, and Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500, Porto Alegre CEP 91501970, RS, Brazil.


Aggregation of jack bean urease (JBU) is involved in many alterations of its biological properties, notably the ureolytic and entomotoxic activities. In order to investigate this phenomenon, protein aggregates were characterized by dynamic (DLS) and static light scattering (SLS) spectroscopies through determination of apparent hydrodynamic radii, the average molecular masses, radii of gyration and second virial coefficients. No effect of disulfide reducing agents on protein association was observed contrasting with previous reports implicating their function in the prevention of JBU aggregation. The influence of freeze-thawing cycles on protein aggregation was also investigated. Our results showed that after freeze-thawing cycles the native form of JBU with apparent hydrodynamic radius of 7 nm and radius of gyration of 12 nm is replaced by high-order oligomers and this aggregation is not reverted neither by dithiothreitol (DTT) treatment nor by high concentration of salts. Altogether the data help to understand the complex behavior of JBU in solution and may correlate with the diversity of biological properties of this enzyme.

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