A novel method of preparation of small intestinal brush border membrane vesicles by polyethylene glycol precipitation

A novel method of brush border membrane vesicle (BBMV) preparation from the small intestinal mucosa using polyethylene glycol (PEG) precipitation has been presented. This preparation is compared with calcium-precipitated BBMVs in marker enzyme enrichment, contamination by other subcellular membranes, transport of glucose, and lipid composition. PEG-precipitated BBMVs are comparable with calcium-precipitated membranes in all parameters except lipid composition and thiol content. PEG-precipitated membranes have more phosphatidylcholine and phosphatidylethanolamine and less lysophosphatidyl-choline and lysophosphatidylethanolamine as compared to calcium-precipitated membranes. Diacylglycerol and triacylglycerol content are also high in PEG-precipitated membranes. Alteration in lipid composition indicate the possible activation of lipase and phospholipase by calcium during BBMV preparation, which is not seen in PEG precipitation. Thiol content is almost double in PEG-precipitated membranes as compared to calcium-precipitated membranes. These results indicate that PEG can be used for the preparation of BBMVs in native form from the intestine without any alteration in their structural components, and these membranes show comparable transport activity. (C) 2001 Academic Press.