FIG. 1.

Zymograms of Cel5A:His₆- and CP-grown stationary-phase 2-40 culture supernatants. (A) SDS-8% PAGE gel stained with Coomassie blue. Lanes: M, Bio-Rad Precision Plus molecular weight markers (Bio-Rad, Hercules, CA); 1, ∼5 μg of Cel5A:His₆; 2, ∼15 μg of laminarin-grown culture supernatant; 3, ∼15 μg of Barley β-glucan-grown culture supernatant; 4, ∼15 μg of Avicel-grown culture supernatant. (B) SDS-8% PAGE zymogram containing 0.15% barley β-glucan (medium viscosity; Megazyme, Bray, Ireland). Lanes are as defined in panel A. (C) SDS-8% PAGE zymogram containing 0.1% HE-cellulose (medium viscosity; Fluka). Lanes are as described in panel A. Note the high-molecular-mass bands (✽) in panel B, lane 2, showing three large β-1,3-endoglucanases produced in response to laminarin but not in response to cellulose or barley β-glucan. Also note the appearance of three conserved bands (arrows) in lanes 2 to 4 of panels B and C, suggesting that as many as three β-1,4-endoglucanases function as common members of laminarin, mixed glucan, and cellulose degradative pathways.