TABLE 3.

Inhibition of 3-methylmuconolactone-CoA synthetase by substrate analogues and enzyme-inhibiting agents^a

Inhibitor (concn, mM)	Activity (%)
(+)-Muconolactone	74
2-Methylmuconolactone	94
(+)-4-Methylmuconolactone	96
3,4-Dimethylmuconolactone	68
(−)-3-Ethylmuconolactone	88
3-Methyl-trans-dienelactone	82
p-Chloromercuribenzoate (1)	0
CuCl2 (1)	17
ZnCl2 (1)	0

^aThe enzyme activity was measured by the enzyme-coupled assay described in Materials and Methods, with lactone analogues as inhibitors at a concentration of 0.5 mM. p-Chloromercurybenzoate, CuCl₂, and ZnCl₂ were incubated in the reaction mixture for 5 min prior to addition of the substrate. Activities are relative to those obtained in the absence of inhibitors.