TABLE 1.

UDP-glucosylhydrolase activity of TcdB mutants^a

Mutant	% Hydrolysis
TcdB	27.7 ± 0.45
TcdB1-556	6.9 ± 1.38
TcdB1-500	0.6 ± 0.53
TcdB1-420	0.2 ± 0.51
TcdB1-170	0.7 ± 0.6
TcdB35-556	0.0 ± 0.08
TcdBC365S	6.2 ± 3.1
TcdBC365W	1.23 ± 0.51
TcdBW102A	1.02 ± 0.1

^aGlucosylhydrolase assays were carried out in a reaction mix containing UDP-[¹⁴C]glucose plus TcdB or mutant, and liberated [¹⁴C]glucose was then determined as a percentage of the total counts prior to treatment. The data represent the means of triplicate samples.