title: Milk fat globule membranes. Inhibition by sucrose of the alkaline phosphomonoesterase.
abstract: Sucrose, a widely used agent in the preparation of membranes, inhibited the alkaline phosphomonoesterase of the milk fat globule membrane in both its membrane-bound and detergent-solubilized forms. The inhibition was kinetically competitive and reversible by dialysis. However, its mechanism was more complex than simple competition with substrate because: (a) sucrose induced the appearance of prolonged time-lags in the progress curves of the enzyme; (b) the extent of inhibition and of the time-lags depended on the age of the membrane preparation, the period of pre-exposure of the membranes to sucrose, and the temperature of pre-exposure. On the other hand the acid phosphomonoesterase and the phosphodiesterase activities also present in the membrane preparations were unaffected by the disaccharide.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors*; D000818:Animals; D002417:Cattle; D002462:Cell Membrane; D003956:Dialysis; D005260:Female; D005615:Freezing; D007700:Kinetics; D008055:Lipids; D008566:Membranes; D008892:Milk / Q000201:enzymology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011092:Polyethylene Glycols / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology*
chemical_list: D008055:Lipids; D011092:Polyethylene Glycols; D013395:Sucrose; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D010727:Phosphoric Diester Hydrolases