TABLE 4.

Effect of substrate length on PelX activity

Substrate	Voa (U/mg)	Vmaxb (U/mg)	Kmb
PGA	83	90 ± 10	0.25 ± 0.05 g · liter−1
G2	0
G3	31	40 ± 5	75 ± 10 μM
G4	253	520 ± 30	25 ± 5 μM
G5	148	NDc	ND
G6	142	ND	ND
G7	134	ND	ND

^aThe initial enzymatic rate was measured in 100 mM Tris-HCl (pH 8.5)–0.1 mM CaCl₂–0.5 g of polygalacturonate (PGA) per liter or 0.5 mM oligogalacturonates (G_n, n = 2 to 7). 

^bFor K_m and V_max determination, PelX was incubated with PGA concentrations ranging from 0.025 to 0.25 g · liter⁻¹ and with G_n concentrations ranging from 10 to 100 μM. 

^cND, not determined.