Figure 4
From: Metabolic resistance of the D-peptide RD2 developed for direct elimination of amyloid-β oligomers
RD2 as potential substrate or inhibitor for hDAAO. The emission of a sensitive, fluorogenic reagent at 590 nm was monitored as indication for enzymatic activity. (A) hDAAO was incubated with RD2 or D-alanine. No change in relative emission was detected within 6 h of incubation with RD2, while a substantial increase was observed upon incubation with D-alanine within 2 h. AU: arbitrary unit. (B) hDAAO was incubated with D-serine alone or together with RD2 or sodium benzoate, a known hDAAO inhibitor. hDAAO activity was decreased by 92.8 ± 0.1% on incubation with 625 µM sodium benzoate, while the same concentration of RD2 only slightly affected the enzyme activity (decrease by 9.3 ± 2.1%). The IC50 of sodium benzoate was determined as 7 µM with a four-parameter fit.
