Solubilization of Membrane-Bound Ribonuclease (RNase) and Alkaline Phosphatase from the Isolated Brush Border of Hymenolepis diminuta (Cestoda)

Plasma membrane from the brush border isolated from the tegument of Hymenolepis dimi- nuta contains membrane-bound ribonuclease (RNase) and alkaline phosphatase activities. RNase (yeast RNA substrate), alkaline phosphatase (p-nitrophenyl phosphate substrate), and additional membrane pro- teins were solubilized by sonication or treatment with the detergents dodecyl trimethylammonium bro- mide, /3-octyl-D-glucopyranoside, sodium dodecyl sulfate (SDS), or ZwittergentTM 3-12 (N-dodecyl-N,N- dimethyl-3-ammonio-l-propanesulfonate). At optimal conditions, greater than 90% of both enzymes and total protein were solubilized by the latter two detergents, whereas f3-octyl-D-glucopyranoside, dodecyl trimethylammonium bromide, and sonication were only partially effective. Nonionic detergents did not solubilize the membrane effectively.