What is the Difference Between Rate Zonal and Isopycnic Centrifugation?

The main difference between rate zonal and isopycnic centrifugation lies in the principles of separation and the type of density gradient used. Here are the key differences:

1. Density Gradient: In isopycnic centrifugation, a high-density gradient is used, while a lower density gradient is used in rate zonal centrifugation.
2. Separation Principle: In rate zonal centrifugation, particles are separated based on their size differences, while in isopycnic centrifugation, particles are separated based on their density differences.
3. Sedimentation Rate: Rate zonal centrifugation separates particles according to their sedimentation rates, while isopycnic centrifugation separates particles based on their density, regardless of their sedimentation rates.
4. Independence of Time: Isopycnic centrifugation is independent of time, while rate zonal centrifugation is not.
5. Gradient Shape: The gradient in rate zonal centrifugation is flat, while in isopycnic centrifugation, it is not.

In summary, rate zonal centrifugation is suitable for separating particles based on their size differences, using a lower density gradient, while isopycnic centrifugation is ideal for separating particles based on their density differences, using a higher density gradient.

Comparative Table: Rate Zonal vs Isopycnic Centrifugation

The main difference between rate zonal and isopycnic centrifugation lies in the separation criteria. Here is a comparison table highlighting the key differences between the two methods:

Rate zonal centrifugation separates particles based on their size, shape, and mass, while isopycnic centrifugation separates particles based on their density. The sedimentation rate in rate zonal centrifugation varies depending on the mass of the particles, whereas in isopycnic centrifugation, particles of equal density sediment at the same rate. The gradient in rate zonal centrifugation is flat, whereas the gradient in isopycnic centrifugation is equilibrium (isopycnic). Cross-contamination of particles can occur more easily in rate zonal centrifugation compared to isopycnic centrifugation.