Gradient Fractionation
Gradient Fractionation - Related Videos
03:05
Gradient Centrifugation Based Purification of Nuclei: A Technique to Obtain Ultrapure Fraction of Intact Nuclei Using Density Gradient Centrifugation
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2023
In this video, we describe a simple and efficient protocol using gradient centrifugation to isolate single nuclei. Once isolated, these nuclei can be used for sequencing and genome analysis.
05:56
Polysome Profiling without Gradient Makers or Fractionation Systems
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Cited by 5 •
2021
This protocol describes how to generate a polysome profile without using automated gradient makers or gradient fractionation systems.
08:42
Density Gradient Ultracentrifugation
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2023
Density gradient ultracentrifugation is a common technique used to isolate and purify biomolecules and cell structures. This technique exploits the fact that, in suspension, particles that are more dense than the solvent will sediment, while those that are less dense will float. A high-speed ultracentrifuge is used to accelerate this process in order to separate biomolecules within a density gradient, which can be established by layering liquids of decreasing density in a centrifuge tube. The...
10:19
Cell Fractionation of U937 Cells by Isopycnic Density Gradient Purification
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Cited by 1 •
2021
This fractionation protocol will allow researchers to isolate cytoplasmic, nuclear, mitochondrial, and membrane proteins from mammalian cells. The latter two subcellular fractions are further purified via isopycnic density gradient.
02:15
Density Gradient Purification of Cyanobacterial Plastoglobules
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2025
Source: Shivaiah, K., et al. Plastoglobule Lipid Droplet Isolation from Plant Leaf Tissue and Cyanobacteria. J. Vis. Exp. (2022).This video demonstrates the isolation of plastoglobules from cyanobacteria using sucrose density gradient centrifugation, highlighting their lipid-rich, low-density nature and ensuring their structural preservation for downstream analysis.
FAQs
Particles can resolve through a gradient by two related behaviors. In one, a particle moves until it reaches a position matching its buoyant density, producing a band. In the other, particles separate mainly according to sedimentation rate, so movement through the medium becomes the key basis of resolution. Recognizing which behavior dominates helps researchers interpret where collected material is located.
Size, density, and sedimentation behavior determine how particles move through the gradient. Particles with different properties therefore travel at different rates or stop at different positions. This makes the method useful for resolving mixed biological material rather than treating a sample as uniform. The same separation logic can be applied to cells, organelles, macromolecules, or larger biological particles.
A band forms when particles accumulate at a position whose density matches their buoyant density. Particles that do not reach such a matching position may instead remain distinguishable through differences in sedimentation rate. Band location can therefore provide information about particle behavior in the gradient and help separate materials for later biochemical or structural analysis.
A basic workflow requires a sample, a layered medium that creates a density gradient, and centrifugation to drive particle movement. During centrifugation, the sample’s components migrate through the layers according to their physical behavior. Researchers can then distinguish separated regions or bands and use the resulting fractions for subsequent biochemical or structural examination.
The approach can be applied to a broad range of biological materials, including nuclei, mitochondria, membranes, ribosomes, viruses, and protein complexes. This range is important because these targets differ substantially in scale and composition. Selecting gradient fractionation allows investigators to study particular cellular or molecular components instead of analyzing the entire mixed sample at once.
Separated fractions can support analyses of molecular composition, cellular organization, and particle purity. Researchers may examine isolated material biochemically or structurally, depending on the target and downstream experiment. The separation also helps characterize how components are distributed within a biological sample, providing a more focused basis for interpreting properties of organelles, membranes, complexes, or other particles.