Glycerophosphoinositol inositolphosphodiesterase

The enzyme glycerophosphoinositol inositolphosphodiesterase (EC 3.1.4.43)^[1][2][3][4] is an enzyme that catalyzes the chemical reaction

1-(sn-glycero-3-phospho)-1D-myo-inositol + H₂O ${\displaystyle \rightleftharpoons }$ glycerol + 1D-myo-inositol 1-phosphate

This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric diester bonds. The systematic name is 1-(sn-glycero-3-phospho)-1D-myo-inositol inositolphosphohydrolase. Other names in common use include 1,2-cyclic-inositol-phosphate phosphodiesterase, D-myo-inositol 1:2-cyclic phosphate 2-phosphohydrolase, D-inositol 1,2-cyclic phosphate 2-phosphohydrolase, D-myo-inositol 1,2-cyclic phosphate 2-phosphohydrolase, 1-D-myo-inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase, and inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase.

This enzyme 1-D-myo-inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase, was reported to be identical to annexin III.^[5] Sekar and co-workers ^[6] clearly demonstrated the dissociation of 1-D-myo-inositol-1,2-cyclic-phosphate 2-inositolphosphohydrolase activity from annexin III. Perron and co-workers confirmed on the basis of structural studies that annexin III did not possess an enzymatic activity.^[7] While the physiological significance of this enzymatic activity is still not clear, Sekar et al. [Biochem. Mol. Med. 61:95-100, 1007] reported over 10-fold increased release of this enzymatic activity in several patients admitted to the hospital's intensive care unit.^[8]