FIGURE 7.

Effects of BBMV on starch degradation by PPA. Various amounts of BBMV before (A) or after (B) heat treatment at 98 °C for 20 min to inactivate the BBM proteins were diluted to 0.56–167 μg/ml (25 μl) with the buffer containing 1 mm phlorizin, added to PPA (0.56 μg/ml (10 nm), 25 μl), and preincubated at 37 °C for 15 min. Then 0.1 ml of 1% soluble starch was added and reacted at 37 °C for 30 min, and the starch-degrading activity was measured by the concentration of reducing sugars, as described under “Experimental Procedures.” The ordinate axis shows the PPA activity by taking that of standard PPA without BBMV as 100%. ▨, BBMV only; ■, PPA + BBMV. The experiment was carried out in duplicate and repeated three times. The data represent the means ± S.E. (error bars) (n = 3) and were analyzed by Student's t test after correcting the activity value for (PPA + BBMV) by subtracting the value for BBMV (A) or correcting the value for (PPA + heated BBMV) by subtracting the value for heated BBMV (B). *, p < 0.05; **, p < 0.01 compared with that in the absence of BBMV.