Background: Prion proteins may adopt multiple aggregate conformations, known as strains. Results: Kosmotropic and chaotropic anions exhibit opposite effects on aggregation kinetics and favor different strains. Conclusion: Both prion nucleation kinetics and prevailing strain patterns strongly depend on ionic composition of the aggregation mixture. Significance: Ionic composition is shown to be a critical determinant in the generation of prion strains.

Aims: The present study aimed at isolating new source of uricase producers from Malaysian hot springs together with partial purification and characterization of thermophilic uricase from novel strain. Methodology and results: A bacteria strain, designated as SN4, was found to have the ability to degrade uric acid. 16S rRNA analysis identified SN4 as Pseudomonas otitidis. Uricase was then extracted from SN4 and purification was performed via ammonium sulphate precipitation. The effects of temperature, pH and metal ions on partially purified uricase were evaluated. Results showed that 70% ammonium sulphate concentration gave the highest uricase activity at 4.18 U/mL compared to other concentrations. The molecular weight of the partially purified uricase was 33 kilodalton (kDa). The optimum temperature for uricase was 45 °C and its activity was highest at pH 8.0. Calcium ions and copper ions enhanced uricase activity while cobalt ions reduced uricase activity. Conclusion, significance and impact of study: Isolation and investigation of uricase producers from new sources such as thermophiles would increase availability and thermal stability of the uricase that could be used for significant purposes such as in biochemical and clinical applications.