Modified colorimetric assay for uricase activity and a screen for mutant Bacillus subtilis uricase genes following StEP mutagenesis

Su Hua Huang, Tung-Kung Wu*

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

This study describes a modified colorimetric assay for uricase activity in flexible 96-well microtiter plates using the uricase/ uric acid/horseradish peroxidase/4-aminoantipyrine/3,5-dichloro-2-hydroxybenzene sulfonate colorimetric reaction. The utility of this assay was demonstrated in a screen for mutant uricase enzymes derived from the uricase gene of the thermophilic bacterium Bacillus subtilis by a modified staggered extension process (StEP) mutagenesis. An Escherichia coli library of StEP-derived uricase mutant clones was screened yielding two identical active mutant uricase genes. Two motifs conserved in eukaryotic and prokaryotic uricases are highly conserved in the mutant uricase. The mutant uricase protein was found to exhibit high uricase activity (13.1 U·mg-1). Finally, the modified colorimetric method is much more efficient than the conventional ones and greatly reduces assay time from 4 days to less than 20 h.

Original languageEnglish
Pages (from-to)517-523
Number of pages7
JournalEuropean Journal of Biochemistry
Volume271
Issue number3
DOIs
StatePublished - 1 Feb 2004

Keywords

  • Bacillus subtilis uricase gene
  • Horseradish peroxidase
  • Maltose binding protein
  • Modified colorimetric assay
  • Staggered extension process (StEP)

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