TABLE 4.

Activity of Abn2 against arabinose-containing substrates and biochemical properties^c

Substrate	Enzymatic activity (U mg−1)a
Linear α-1,5-l-arabinan	72.8 ± 1.2
Sugar beet arabinan (branched)	51.3 ± 2.4
Pectin (apple)	10.0 ± 1.6
Larch wood arabinogalactan	NAb
Wheat arabinoxylan	NAb
p-Nitrophenyl-α-l-arabinofuranoside	NAb

^aActivity was assayed by incubating purified recombinant Abn2 with substrates at 37°C, pH 6.6. The data shown are the averages ± standard deviations of three independent experiments, each performed in duplicate measurements.

^bNA, no detectable activity.

^cFor Abn2 (YxiA), the M_r was 46 kDa, the optimum pH at 37°C was 7.0, and the optimum temperature at pH 6.6 was 50°C. The K_m of 2.0 ± 0.24 (mg ml⁻¹) and V_max of 0.25 ± 0.012 (mmol min⁻¹ mg⁻¹) were determined at 50°C, pH 7.0, by using linear α-1,5-l-arabinan as substrate. These data are the averages ± standard deviations of three independent experiments, each performed in duplicate measurements.