FIGURE 6.

Essential role of Arg⁶⁷⁰ in hydrolyzing activity of DPP11. A, the hydrolyzing activities of wild type PeDPP11 (2 ng) and with substitution of Gly, Lys, His, Gln, or Asp (0.5 μg) were measured with LD-MCA (open column) or LE-MCA (closed column). B, the ratio of hydrolysis of LD-MCA to that of LE-MCA was plotted against the van der Waals volumes of the amino acids at position 670. Data for the Asp substitution were not plotted, as there were no activities for either substrate. C, the hydrolyzing activities of wild type PeDPP11 (open symbol) and R670H (closed symbol) were determined with LE-MCA in 50 mm sodium acetate (circle), sodium phosphate (square), and Tris-HCl (triangle).