Figure 5.

Activity of Stisa Proteins in Debranching Glucan.

(A) E. coli expressing Stisa1 (1), Stisa2 (2), and Stisa3 (3) grown to the stationary phase and stained with iodine vapor. C indicates a control strain carrying empty vector. Colonies expressing Stisa1 and Stisa3 stained blue, whereas the control and Stisa2 colonies stained very light red/brown.

(B) Activities of mixtures of Stisa proteins on amylopectin, β-limit dextrin, phytoglycogen, boiled potato starch, and nonboiled starch granules. The equivalent average activity for each isoamylase alone is indicated by a colored bar in the first column: red for Stisa1, yellow for Stisa2, and light blue for Stisa3. These activities of each isoform are represented by the size of the bar of the appropriate color only but are shown one atop the other for ease of comparison and to identify additive interactions in the mixtures. The dark blue columns indicate the activities of the mixtures of isoforms as labeled below each column, with the standard deviations calculated from three different assays with two different preparations of proteins from E. coli. Combo refers to the activity of Stisa1, Stisa2, and Stisa3 mixed together.