Assay of 1 l- myo-inositol-1-phosphatase using a fluorometric method

• Published in: Analytical biochemistry Vol. 198; no. 2; pp. 375 - 378
• Main Authors: Churchich, Jorge E., Kwok, Francis
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1991
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/0003-2697(91)90442-V

1 l- myo-Inositol-1-phosphatase, an enzyme purified from brain tissues, catalyzes the dephosphorylation of 1 l- myo-inositol 1-phosphate. This enzyme has become the subject of intense research interest, since myo-inositol is needed for the resynthesis of phosphatidylinositol. We have developed a sensitive fluorometric assay for detecting the activity of 1 l- myo-inositol-1-phosphatase. The assay is based on o-aminobenzoyl β-glycerophosphate fluorescence, according to the following principles: (I) The fluorescence yield of o-aminobenzoyl β-glycerophosphate is increased by 2.75-fold in the presence of saturating concentrations of bovine serum albumin. (II) o-Aminobenzoyl β-glycerophosphate has the same fluorescence yield as o-aminobenzoyl glycerol, but the latter does not bind to bovine serum albumin. (III) Dephosphorylation of the substrate, catalyzed by the monophosphatase, makes less o-aminobenzoyl β-glycerophosphate available for binding to bovine serum albumin, thereby producing a decrease in the fluorescence intensity.