Purification and properties of myo-inositol-1-phosphatase from bovine brain

Biochem J. 1988 Jul 15;253(2):387-94. doi: 10.1042/bj2530387.

Abstract

myo-Inositol-1-phosphatase from bovine brain was purified over 2000-fold. The native enzyme has a Mr of 59,000, and on SDS/polyacrylamide-gel electrophoresis the subunit Mr was 31,000. Thus the native enzyme is a dimer of two apparently identical subunits. The enzyme, purified to a specific activity of more than 300 units/mg of protein (1 unit of enzyme activity corresponds to the release of 1 mumol of Pi/h at 37 degrees C), catalysed the hydrolysis of a variety of phosphorylated compounds, the best one, in terms of V/Km, being D-myo-inositol 1-phosphate. Kinetic constants of compounds tested, including both isomers of glycerophosphate and two deoxy forms of beta-glycerophosphate, were measured. They show the importance of the two hydroxyl groups which are adjacent to the phosphate in myo-inositol 1-phosphate. With a wide variety of substrates Li+ was found to be an uncompetitive inhibitor whose Ki varied with substrate structure.

MeSH terms

  • Adenosine Monophosphate / metabolism
  • Animals
  • Brain / enzymology*
  • Cattle
  • Chromatography, Gel
  • Electrophoresis, Polyacrylamide Gel
  • Inositol Phosphates / metabolism
  • Lithium / pharmacology
  • Organophosphorus Compounds / chemical synthesis
  • Organophosphorus Compounds / metabolism
  • Phosphoric Monoester Hydrolases / antagonists & inhibitors
  • Phosphoric Monoester Hydrolases / isolation & purification*
  • Phosphoric Monoester Hydrolases / metabolism
  • Substrate Specificity

Substances

  • Inositol Phosphates
  • Organophosphorus Compounds
  • propan-1-ol 2-phosphate
  • inositol 1-phosphate
  • Adenosine Monophosphate
  • Lithium
  • Phosphoric Monoester Hydrolases
  • myo-inositol-1 (or 4)-monophosphatase