Proteomics/Protein Separations - Centrifugation/Preparative Centrifugation vs. Analytical Centrifugation

__FORCETOC__ Table of Contents: Protein Separations - Centrifugation History of the Centrifuge How the Centrifuge Works Density Gradient Centrifugation Differential Centrifugation Preparative Centrifugation vs. Analytical Centrifugation Two types of ultracentrifuges developed: analytical and preparative Analytical · Uses small sample size (less than 1 ml) · Built in optical system to analyze progress of molecules during centrifugation · Uses relatively pure sample · Used to precisely determine sedimentation coefficient and MW of molecules · Beckman Model E is an example of centrifuge used for these purposes. Preparative · Larger sample size can be used · No optical read-out – collect fractions and analyze them after the run · Less pure sample can be used · Can be used to estimate sedimentation coefficient and MW · Generally used to separate organelles and molecules. Most centrifugation work done using preparative ultracentrifuge · Several models available, including L5-65 and L5-75 used for preparative purposes.