Optimization And Stabilization Of An Ultra Sensitive Biosensor For The Determination Of Inorganic Phosphate By Enzymatic Amplification

A new, highly sensitive enzyme sensor was developed for the determination of inorganic phosphate using maltose phosphorylase, acid phosphatase, glucose oxidase and mutarotase. Maltose phosphorylase from Lactobacillus brevis was purified to 98 % by a simple FPLC-aided procedure, including anion exchange chromatography, gel filtration and hydroxyapatite chromatography. The combination of the first two enzymes generates two glucose molecules per reaction cycle and recycles one molecule of phosphate. Finally, the oxidation of glucose is catalysed by mutarotase and glucose oxidase. Thus, a detection limit of 10/sup -8/ M was obtained and the sensor response was linear in the range 0.1-1 /spl mu/M, which is relevant for the monitoring of water pollution.