Figure 3. Effect of LAB on the activities of enzymes of starch degradation.

(a) Effect of inhibitors on α-amylase activity. Extracts of endosperm from seedlings at the dpi indicated were assayed for α-amylase activity in the absence (black bars) or in the presence of 500 μM (dark grey bars) or 100 μM (light grey bars) LAB, or acarbose, a known inhibitor of the enzyme (500 μM; white bars). Values are means ± SE of measurements on three independent extracts. (b) Effect of inhibitors on β-amylase activity. Extracts as in (a) were assayed for β-amylase activity either in the absence (black bars) or in the presence of 500 μM (dark grey bars) or 100 μM (light grey bars) LAB. Values are means ± SE of measurements on three independent extracts. (c) Effect of inhibitors on limit dextrinase activity. Activity of purified recombinant limit dextrinase was assayed against pullulan in the absence of inhibitors (black bar) or in the presence of 500 μM (dark grey bars), 100 μM (light grey bars), or 50 μM (white bars) of LAB, or β-cyclodextrin (βCD), a known inhibitor of the enzyme. Values are means ± SE of three independent measurements. (d) Effect of inhibitors on maltase (Agl97) activity. Purified recombinant Agl97 was assayed with pNPG in the presence of 100 μM (black bars), 10 μM (dark grey bars), 1 μM (grey bars), 0.1 μM (light grey bars), or 0.01 μM (white bars) of LAB, xyloDNJ or deoxynojirimycin (DNJ), a known inhibitor of the enzyme³¹. Results are expressed as percent inhibition relative to control assays with no inhibitor. The enzyme preparation was as previously specified³¹.