Purification and characterization of phosphatidylinositol kinase from porcine liver microsomes

• Published in: Biochimica et biophysica acta Vol. 959; no. 1; pp. 67 - 75
• Main Authors: Hou, W M, Zhang, Z L, Tai, H H
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 04.03.1988; North-Holland
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Cations, Divalent; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Kinetics; Microsomes, Liver - enzymology; Molecular Weight; Phosphotransferases (Alcohol Group Acceptor); Phosphotransferases - isolation & purification; Phosphotransferases - metabolism; Swine; Transferases; Purification; Antibody; Gel electrophoresis; Enzyme; Liver; Stimulation; Microsome; Ion exchange chromatography; Pig; Vertebrata; Mammalia; Immunoblotting assay; Phosphatidylinositol kinase; Artiodactyla; Divalent cation; Ungulata
• ISSN: 0006-3002; 1878-2434

Phosphatidylinositol kinase was solubilized and purified from porcine liver microsomes to apparent homogeneity. The purification procedure includes: solubilization of microsomes by 2% Triton X-100, ammonium sulfate precipitation (20-35% saturation), Reactive blue agarose chromatography, DEAE-Sephacel chromatography and two consecutive hydroxyapatite chromatographies. A total of 4900-fold purification with 8% recovery of enzyme activity was achieved. The molecular weight of the enzyme as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 55000. The enzyme is stimulated in a decreasing order by Mg2+, Fe2+, Mn2+, Fe3+ and Co2+. Ca2+ inhibited Mg2+-stimulated activity with an I50 of 0.4 mM. Apparent Km values for phosphatidylinositol and ATP are 120 and 60 microM, respectively. The enzyme is inhibited by adenosine (I50 = 70 microM), ADP (I50 = 120 microM) and quercetin (I50 = 100 microM). The enzyme is also sensitive to sulfhydryl inhibitors. Using the purified enzyme as an immunogen, we have successfully prepared antibodies for phosphatidylinositol kinase in rabbits. The antibodies appear to recognize an antigen of Mr 55000 on SDS-polyacrylamide gel electrophoresis from various porcine tissues in Western blot analysis.