Figure 5

PQQGDH activity for glucose in the presence of individual peptides. (A) The PQQGDH activities were measured in the presence of the synthetic peptides. The enzymatic activities for glucose are shown in the SV plot. The enzyme assay was performed with 0.57 nM PQQGDH and 20 μM of each peptide. The samples contained the following: no peptide, (●); GEKD, (○); GERD, (□); SERG, (■); DDDD, (×). (B) Linewaver-Burk plot of PQQGDH activities in the presence of 0 μM SERG (●), 2 μM SERG (△), 10 μM SERG (○), and 20 μM SERG (■). All of the correlation coefficients (R²) were > 0.98. The X-axis shows the reciprocal values of the glucose concentration, and the Y-axis indicates the reciprocal values of the kinase activity. (C) PQQGDH activities of the wild-type (●), with 0.2 μM peptide (×), with 1 μM peptide (□), with 2 μM peptide (△), with 20 μM peptide (■) were plotted against different glucose concentrations. The SERG peptide was used in the concentration range of 0.2–20 μM.