TABLE 3.

Effects of thiol reagents and metal ions on PDC hydrolase activity^a

Reagent	Concn (mM)	Relative activity (%)
		PDC hydrolysis	PDC synthesis
None		100	100
Ellman’s reagent	0.1	10	20
N-Ethylmaleimide	1	5	6
Iodoacetic acid	1	90	90
MnCl2 · 4H2O	0.2	100	100
CoCl2 · 6H2O	0.2	100	100
CuSO4 · 5H2O	0.2	100	40
ZnSO4 · 7H2O	0.2	5	10

^aPurified LigI (0.5 μg) was preincubated with each reagent at 30°C for 10 min, and the remaining activities were determined.