Editor: Barbara Bakker
Characterization of the Saccharomyces cerevisiae galactose mutarotase/UDP-galactose 4-epimerase protein, Gal10p
Article first published online: 24 JAN 2007
FEMS Yeast Research
Volume 7, Issue 3, pages 366–371, May 2007
How to Cite
Scott, A. and Timson, D. J. (2007), Characterization of the Saccharomyces cerevisiae galactose mutarotase/UDP-galactose 4-epimerase protein, Gal10p. FEMS Yeast Research, 7: 366–371. doi: 10.1111/j.1567-1364.2006.00204.x
- Issue published online: 5 FEB 2007
- Article first published online: 24 JAN 2007
- Received 23 June 2006; revised 18 September 2006; accepted 28 September 2006.First published online 24 January 2007.
- leloir pathway;
- SDR family enzyme;
- galactose metabolism;
- bifunctional enzyme;
- aldose epimerase
Saccharomyces cerevisiae and some related yeasts are unusual in that two of the enzyme activities (galactose mutarotase and UDP-galactose 4-epimerase) required for the Leloir pathway of d-galactose catabolism are contained within a single protein–Gal10p. The recently solved structure of the protein shows that the two domains are separate and have similar folds to the separate enzymes from other species. The biochemical properties of Gal10p have been investigated using recombinant protein expressed in, and purified from, Escherichia coli. Protein–protein crosslinking confirmed that Gal10p is a dimer in solution and this state is unaffected by the presence of substrates. The steady-state kinetic parameters of the epimerase reaction are similar to those of the human enzyme, and are not affected by simultaneous activity at the mutarotase active site. The mutarotase active site has a strong preference for galactose over glucose, and is not affected by simultaneous epimerase activity. This absence of reciprocal kinetic effects between the active sites suggests that they act independently and do not influence or regulate each other.