Density gradient ultracentrifugation (DGUC)
Plasma made cell-free by centrifugation at 5000 g for 30 min at 4°C or other mixtures were incubated with or without sugar molecules for 2 h at 4°C and density increased to 1.24 g/cc by adding solid KBr. Resulting solution (1.1 ml in 1.3 ml tubes) was centrifuged in a Himac CS 150 GXII microcentrifuge (HITACHI) at 535000 g for 4 h at 4°C. The middle (400 µl) and bottom (300 µl) layers were separately saved.