Main Difference – Preparative vs Analytical Centrifugation
Centrifugation is a separation method in which the application of the centrifugal force sediments or fractionates a heterogeneous mixture. Microcentrifugation, high-velocity centrifugation, and ultracentrifugation are the three types of centrifugation based on the volume and speed used in the process. Among other centrifugation methods, ultracentrifugation uses the maximum angular velocity. The rotating speed of ultracentrifugation is as high as 1 000 000 g. Thus, ultracentrifugation is used to isolate small particles such as ribosomes, proteins, and viruses. Preparative and analytical centrifugation are the two types of ultracentrifugation methods. The main difference between preparative and analytical centrifugation is that preparative centrifugation is used in pelleting small materials such as membranes, organelles, viruses, DNA and RNA whereas analytical centrifugation is used to determine the mass and shape of macromolecules such as protein complexes and rate of sedimentation of molecules.
Key Areas Covered
1. What is Preparative Centrifugation
– Definition, Facts, Uses
2. What is Analytical Centrifugation
– Definition, Facts, Uses
3. What are the Similarities Between Preparative and Analytical Centrifugation
– Outline of Common Features
4. What is the Difference Between Preparative and Analytical Centrifugation
– Comparison of Key Differences
Key Terms: Analytical Centrifugation, Analytical Processes, Density Gradient Centrifugation, High-velocity Centrifuge, Preparative Centrifugation, Small Particles
What is Preparative Centrifugation
Preparative centrifugation refers to a high-velocity centrifuge used in the separation of small submicroscopic particles. It separates small particles such as viruses, viral particles, protein complexes, proteins, lipoproteins, RNA, and plasmid DNA. A Beckman-Coulter preparative centrifuge with its rotor inside is shown in figure 1.
Figure 1: Beckman-Coulter Preparative Centrifuge
The preparative centrifugation can also be used as a density gradient centrifugation method. The sucrose gradient can be used to separate cellular organelles. Caesium gradient can be used to separate nucleic acids.
What is Analytical Centrifugation
Analytical centrifugation refers to a high-velocity centrifuge used in the analytical processes. It is used to obtain information about the types of molecules in a particular sample by knowing the overall shape, conformational changes, and stoichiometry of the subunits. It can also be used to determine the sedimentation rate of particles. An ultracentrifuge is shown in figure 2.
Figure 2: Beckman Coulter Optima LE-80K Ultracentrifuge
An optical detection system is provided with the analytical centrifuge to monitor the spinning of the sample in real time. Sedimentation velocity experiments and sedimentation equilibrium experiments are the two main types of experiments performed with analytical centrifugation.
Similarities Between Preparative and Analytical Centrifugation
- Both preparative and analytical centrifugation are types of ultracentrifugation methods operated at high speeds such as 1 000 000 g.
- Both preparative and analytical centrifugation are used to separate small particles.
Difference Between Preparative and Analytical Centrifugation
Definition
Preparative Centrifugation: Preparative centrifugation refers to a high-velocity centrifuge used in the separation of small submicroscopic particles.
Analytical Centrifugation: Analytical centrifugation refers to a high-velocity centrifuge used in the analytical processes.
Analytical Procedures
Preparative Centrifugation: Preparative centrifugation cannot be used in analytical procedures.
Analytical Centrifugation: Analytical centrifugation is used in analytical procedures.
Type of Samples
Preparative Centrifugation: Preparative centrifugation is used in pelleting small materials such as membranes, organelles, viruses, plasmid DNA, and RNA.
Analytical Centrifugation: Analytical centrifugation is used to determine the mass and shape of macromolecules such as protein complexes and rate of sedimentation of molecules.
Sample Volume
Preparative Centrifugation: A large sample size can be processed in preparative centrifigation.
Analytical Centrifugation: Only small sample volumes (less than 1 mL) can be processed by analytical centrifugation.
Purity of the Sample
Preparative Centrifugation: Less pure samples can be used in preparative centrifugation.
Analytical Centrifugation: Relatively pure samples are used in the analytical centrifugation.
Sedimentation Coefficient and Molecular Weight
Preparative Centrifugation: Preparative centrifugation can be used to determine the sedimentation coefficient and molecular weight.
Analytical Centrifugation: A precise sedimentation coefficient and molecular weight are used in analytical centrifugation.
Optical Read-out
Preparative Centrifugation: The fractions can be collected after the run in preparative centrifugation, and there is no optical read-out during the run.
Analytical Centrifugation: The progress of the analytical centrifugation can be observed visually during analytical centrifugation.
Cooling Arrangements
Preparative Centrifugation: No cooling arrangements are used in the preparative centrifugation.
Analytical Centrifugation: As high speed generates more heat, a cooling arrangement should be used in the analytical centrifugation
Type of Machines
Preparative Centrifugation: L5-65 and L5-75 are used in the preparative centrifugation.
Analytical Centrifugation: Beckman Model E is used in the analytical centrifugation.
Conclusion
Preparative and analytical centrifugation are the two types of ultracentrifugation methods that use high-velocity centrifugation. Preparative centrifugation is used to separate small particles such as ribosomes, plasmid DNA, and RNA. However, analytical centrifugation is mainly used to obtain analytical measurements of the sample. The main difference between preparative and analytical centrifugation is the purpose of each type of centrifugation during sample processing.
Reference:
1. Aswathi K S, Student at central university of kerala Follow. “Ultracentrifugation.” LinkedIn SlideShare, 17 Nov. 2015, Available here.
Image Courtesy:
1. “Beckman-Coulter preparative centrifuge Avanti J25-03” By real name: Matylda Sękpl.wiki: Cygaretkacommons: Cygaretka – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Ultracentrifuge”By Mlw3559 at English Wikibooks (CC BY-SA 2.5) via Commons Wikimedia
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