Release of remnant plasma membrane from milk fat globules by Triton X-100

The nonionic detergent, Triton X-100, was investigated as an agent for releasing plasma membrane from milk fat globules. The sedimentable material (50 000 X g, 1 h) derived by treating washed goat globules with the detergent (0.2%) was compared to membrane made by the classical globule churning procedure. Characterization included lipid and protein analyses, gel electrophoresis of peptide components, determination of enzymatic activities, and examination with the electron microscope. The results established that the detergent-releasing material is membrane with similarities to the product by churning. Evaluation of variables revealed that a detergent concentration of 0.1 to 0.2% and reaction temperature of 20-22 degrees C appear optimum with respect to membrane yield when a reaction time of 2 min is employed. At higher detergent concentrations or temperatures removal of phospholipid from the membrane was maximized. Triton X-100 was observed to release membrane from milk fat globules of the goat, human and cow, the latter with a minor procedural modification. The detergent based method is a convenient procedure for obtaining plasma membrane material in good yield for biochemical studies. It also should aid investigations of milk fat globule structure.