TABLE 2.

Kinetic constants of yeast esterase on different compounds functioning as substrates for the enzyme^a

Substrate	Km (mM)	Vmax/mg of protein (U/mg)	kcat/Km (mol−1 s−1)
α-Naphthyl acetate	0.86	19	1.5 × 104
4-Methylumbelliferyl acetate	0.076	15	1.3 × 105
p-Nitrophenyl acetate	0.35	12	2.3 × 104
Carboxyfluorescein diacetate	0.056	15	1.8 × 105
S-Formylglutathione	0.88	220	1.7 × 105

^aK_m and V_max values for the substrates were determined with the most purified enzyme preparation. The k_cat is V_max/[E]_T, where [E]_T is the (total) concentration of the enzyme. Activities for S-formylglutathione were measured in 50 mM potassium phosphate (pH 7.0) at 30°C.