title: A phospholipid-deacylating system of bacteria active in a frozen medium.
abstract: A phosphatidylcholine-deacylating system present in a Butyrivibrio species (probably fibrisolvens) shows appreciable activity at low temperatures with a maximum hydrolysis rate at--10 degrees C. 2. The rate at--10 degrees C is higher than at 39 degrees C unless the system at the latter temperature is stimulated by adding oleic acid or sodium dodecyl sulphate. 3. The low-temperature phospholipase activity has an absolute requirement for thiol reagents, e.g. cysteine, dithiothreitol or mercaptoethanol. 4. Ca2+, Mg2+ and Mn2+ stimulate the activity up to 10 mM, but EDTA inhibits; higher concentrations of Ca2+ also inhibit. 5. The enhancement of activity at low temperatures appears not to be associated with a crystalline change in the hydrated phospholipid substrate, but depends on the formation of a solid phase in the incubation medium which brings the substrate and bacterial cells into juxtaposition or causes fusion.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002151:Calorimetry; D003545:Cysteine / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D005051:Eubacterium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005615:Freezing; D005978:Glutathione / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008623:Mercaptoethanol / Q000494:pharmacology; D009829:Oleic Acids / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000378:metabolism*; D010740:Phospholipases / Q000032:analysis; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013696:Temperature
chemical_list: D009829:Oleic Acids; D010713:Phosphatidylcholines; D012967:Sodium Dodecyl Sulfate; D008345:Manganese; D008623:Mercaptoethanol; D010740:Phospholipases; D005978:Glutathione; D008274:Magnesium; D003545:Cysteine; D002118:Calcium; D004229:Dithiothreitol