What is Isopycnic (sucrose density) Centrifugation?
a sucrose density gradient is created by gently overlaying lower concentrations of sucrose on higher concentrations in a centrifuge tube. The sample containing organelles of different bouyant densities (lipid and protein content) is placed on top of the gradient and centrifuged at forces in excess of 150,000 x g. The particles travel through the gradient until they reach the point in the gradient at which their density matches that of the surrounding sucrose. This fraction can then be removed and subjected to further analysis. After it becomes known between which two layers the required fraction finally settles, a simplified setup with just these two layers may be used.