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. Author manuscript; available in PMC: 2012 Dec 15.

Published in final edited form as: Anal Biochem. 2011 Aug 16;419(2):106–109. doi: 10.1016/j.ab.2011.08.018

Fig. 1 — Extraction of D-serine from plasma by SPE and subsequent determination of D-serine levels using the DAAO enzyme coupled assay - (A) D-serine at various concentrations was added to plasma in the presence of 100 μM CBIO (filled squares, solid line) or 1 % DMSO vehicle (empty circles, dashed line). D-serine was separated from CBIO by solid phase extraction. Subsequently, D-serine concentrations were determined using the DAAO-catalyzed conversion of D-serine to fluorescent resorufin in the DAAO enzyme coupled assay (materials and methods). Fluorescence readings (n = 2) in relative fluorescent units (RFU) were obtained from end point measurements after the DAAO reaction was allowed to go completion. Single measurements are shown. A fluorescence (RFU) vs. D-serine (μM) standard curve was constructed with each experiment. (B) Kinetic trace of resorufin resulting from D-serine oxidation. D-serine (250 μM) ± CBIO (100 μM) were added to plasma, and SPE/DAAO analysis was used to monitor D-serine concentrations at different time points during the DAAO-catalyzed oxidation. D-serine only: empty circles, dashed line. D-serine + CBIO: filled circles, solid line. Data points at each concentration are duplicates.

Fig. 1 — Extraction of D-serine from plasma by SPE and subsequent determination of D-serine levels using the DAAO enzyme coupled assay - (A) D-serine at various concentrations was added to plasma in the presence of 100 μM CBIO (filled squares, solid line) or 1 % DMSO vehicle (empty circles, dashed line). D-serine was separated from CBIO by solid phase extraction. Subsequently, D-serine concentrations were determined using the DAAO-catalyzed conversion of D-serine to fluorescent resorufin in the DAAO enzyme coupled assay (materials and methods). Fluorescence readings (n = 2) in relative fluorescent units (RFU) were obtained from end point measurements after the DAAO reaction was allowed to go completion. Single measurements are shown. A fluorescence (RFU) vs. D-serine (μM) standard curve was constructed with each experiment. (B) Kinetic trace of resorufin resulting from D-serine oxidation. D-serine (250 μM) ± CBIO (100 μM) were added to plasma, and SPE/DAAO analysis was used to monitor D-serine concentrations at different time points during the DAAO-catalyzed oxidation. D-serine only: empty circles, dashed line. D-serine + CBIO: filled circles, solid line. Data points at each concentration are duplicates.