FIG. 1.
Sensitivity of LT, LT-K63, LT-G192, and LT-K63/G192 protease activity. The structural subunits of LT are highlighted. The smallest protein is the monomeric form of the B subunit (Bm). The remaining two proteins are the uncleaved enzymatically active A subunit and the proteolytically cleaved A1 subunit. (A) Proteolytic breakdown products after treatment of the proteins with trypsin for 90 min under nondenaturing conditions; (B) breakdown pattern observed after incubation with trypsin for 5 min under denaturing conditions; (C) breakdown pattern observed after incubation with trypsin for 15 min under denaturing conditions; (D) proteolytic breakdown pattern of the proteins after incubation with protease-rich intestinal lavage fluid.