Cloning, expression and characterization of a UDP-galactose 4-epimerase from Escherichia coli

Xi Chen, Przemyslaw Kowal, Sarah Hamad, Hongni Fan, Peng George Wang

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


The gene galE encoding UDP-galactose 4-epimerase was cloned into E. coli BL21(DE3) from the chromosomal DNA of E. coli strain K-12. High expression of the soluble recombinant epimerase was achieved in the cell lysate. In order to evaluate the use of this epimerase in enzymatic synthesis of important α- Gal epitopes (oligosaccharides with a terminal Galα1,3Gal sequence), a new radioactivity assay (α1,3-galactosyltransferase coupled assay) was established to characterize its activity in producing UDP-galactose from UDP- glucose. Approximately 2700 units (100 mg) enzyme with a specific activity of 27 U mg-1 protein could be obtained from one liter of bacterial culture. The epimerase was active in a wide pH range with an optimum at pH 7.0. This expression system established a viable route to the enzymatic production of α-Gal oligosaccharides to support xenotransplantation research.

Original languageEnglish (US)
Pages (from-to)1131-1135
Number of pages5
JournalBiotechnology Letters
Issue number12
StatePublished - 1999
Externally publishedYes


  • α 1,3-galactosyltransferase
  • Cloning
  • E. coli
  • Expression
  • UDP-galactose 4- epimerase

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology
  • Microbiology


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