Polyphosphoinositide phospholipase C in wheat root plasma membranes. Partial purification and characterization.
The effect of various detergents on polyphosphoinositide-specific phospholipase C activity in highly purified wheat root plasma membrane vesicles was examined. The plasma membrane-bound enzyme was solubilized in octylglucoside and purified 25-fold by hydroxylapatite and ion-exchange chromatography. The purified enzyme catalyzed the hydrolysis of phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) with specific activities of 5 and 10 mumol/min per mg protein, respectively. Phosphatidylinositol (PI) was not a substrate. Optimum activity was between pH 6-7 (PIP) and pH 6-6.5 (PIP2). The enzyme was dependent on micromolar concentrations of Ca2+ for activity, and millimolar Mg2+ further increased the activity. Other divalent cations (4 mM Ca2+, Mn2+ and Co2+) inhibited (PIP2 as substrate) or enhanced (PIP as substrate) phospholipase C activity.
Melin
P M
PM
Department of Biochemistry, University of Lund, Sweden.
Pical
C
C
Jergil
B
B
Sommarin
M
M
D002118:Calcium / Q000494:pharmacology; D002384:Catalysis; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D003902:Detergents; D006868:Hydrolysis; D015636:Magnesium Chloride / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry / Q000302:isolation & purification*; D013379:Substrate Specificity; D014908:Triticum / Q000187:drug effects / Q000201:enzymology*
D003902:Detergents; D015636:Magnesium Chloride; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D002118:Calcium