| dc.description.abstract | We describe the characterization and application of quercetin pentaphosphate (QPP), a new
fluorimetric substrate for the detection of alkaline phosphatase (ALP) activity. QPP exhibits
major absorbance peaks at 260/ 410 nm and a strong fluorescent at λex/λem = 425/510 nm at
alkaline pH. The product of enzymatic reaction between QPP and ALP has a strong absorbance
peak at 324 nm with no fluorescence activity at the investigated wavelengths. The product
generated from the enzymatic reaction was found to be proportional to ALP activity and ALP
activity was monitored by absorbance difference at 310 nm and 410 nm. The change in
absorbance was found to be proportional to the ALP concentration with a linear detection range
and a limit of detection of 0.01-16 U/L and 0.766 U L-1, respectively. The enzyme activity was
also monitored by evaluating the change in fluorescence emission at 530 nm with a linear range
of 0.01 – 8 U L-1 and a detection limit of 0.062 U L-1. Further, the validity of the new substrate
for ALP in conjugated form was tested using Bacillus globigii spores as model sample. A
detection limit of 5998 spores/mL was obtained using QPP as a substrate. Unlike the parent
compound, QPP substrate exhibits stability in solution for over three and half months and was
stable under storage for over 12 months. The results obtained demonstrate the effectiveness of
QPP for ALP and compares well with favorably with other fluorescent substrates such as
Fluorescein, Alexsa Fluor and Cy5. | en_US |
