Isopycnic density gradient centrifugation

Some 37 samples from 16 coals of the Pennsylvania State University coal data base (PSOC) were examined. Separate density fractions were obtained by isopycnic density gradient centrifugation of small ( 3iim) coal particles in an aqueous CsCl density gradient. (4J The individual samples are listed by PSOC numbers, coal description, ASTM designation of coal-rank maceral type, and density in Table I. After separation, the samples... 

For zonal density gradient centrifugation there are a number of media that can be used, however the most common of these is sucrose whereas the most common medium for isopycnic density gradient centrifugation is caesium chloride (CSCI2). 

One method for examining the relative density of swollen microgels is through isopycnic density gradient centrifugation (Nolan, Reyes et al. 2005). Using this technique, researchers were able to verify that a denser particle network was formed when a higher concentration of crosslinker was used however, the actual... 

Isopycnic density gradient centrifugation has been used in the characterization of the lipopolysaccharide from Pasturella multocida. Cerulenin, an inhibitor of fatty acid biosynthesis, has been used to induce changes in the fatty acid composition of the lipopolysaccharide of Proteus mirabilis. ... 

Fig. 4. Localization of WAP27 and WAP20 in the crude microsome fractions and the relation with marker-enzyme activities in three organelles (ER, tonoplast, and Golgi). SDS-PAGE of fractionated proteins by isopycnic linear sucrose density gradient centrifugation of microsome fraction of mulberry cortical parenchyma cells was performed using 6-pL samples in each fraction. Immunoblot analysis was performed with anti-WAP27 and anti-WAP20 antibodies. (From ref. [1], with permission from the American Society of Plant Physiologists.)...

Native apoferritin can be prepared by a number of centrifugal methods. Density gradient centrifugation (62) in isopycnic gradients of CsCl or in sucrose have been used to fractionate native ferritin according to its iron content. The native apoferritin sediments with a buoyant density of 1.23, whilst full ferritin has a density in excess of 1.8. Typically using an SW 27 rotor 100 hr are required at 25.000 rpm with a CsCl... 

The density gradient centrifugation process involves a separation in which the supporting liquid varies in density from the top to the bottom of the tube. Two types are common zonal and isopycnic. Figure 39-21 compares differential, zonal, and isopycnic. 

The differences in the buoyant density of biomacromolecules can be exploited for their separation/purification and characterization. The density of DNA is slightly greater than 1.7g/mL, while the density of RNA is more than 1.8g/mL. Proteins have densities less than 1.3g/mL. Therefore, DNA, RNA and proteins can be separated by the CsCl density gradient centrifugation (-200000 x g), also known as isopycnic centrifugation. Since single-stranded DNA (ssDNA) is denser than double-stranded DNA dsDNA), the isopycnic centrifugation can be used to separate the randomly coiled ssDNA and helical dsDNA, which also forms a narrower band. The buoyant density (p) of a DNA molecule, which is related to its G -i- C content by... 

Density-gradient centrifugation, although not readily scalable, is a popular technique for final purification of viruses [Poison, 1993], Either rate-zonal centrifugation, where the separation is based on differences in sedimentation rate, or isopycnic equihbrium centrifugation, where the separation is based solely on density differences, is used. Further details on these techniques can be found in Dobrota and... 

C Isopycnic centrifugation the density gradient forms during centrifugation. Illustration courtesy of Beckman Instruments, Inc. 

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