Influence of pressure and solvent composition on the density gradient in the analytical ultracentrifuge I extended Hermans-Ende equation for the equilibrium density gradient

2008 ◽  
pp. 148-153 ◽  
Author(s):  
M. D. Lechner ◽  
U. Sedlack ◽  
W. Mächtle
Keyword(s):  
Density Gradient ◽  
Solvent Composition ◽  
Equilibrium Density ◽  
Analytical Ultracentrifuge

scholarly journals Analytical subcellular fractionation of needle-biopsy specimens from human liver

1978 ◽  
Vol 174 (2) ◽  
pp. 435-446 ◽  
Author(s):  
T J Peters ◽  
C A Seymour
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Density Gradient ◽  
Needle Biopsy ◽  
Human Liver ◽  
Resolving Power ◽  
Equilibrium Density ◽  
Marker Enzyme ◽  
Acid Hydrolases ◽  
Biopsy Specimens

1. Fragments (2-20 mg wet wt.) of closed needle-biopsy specimens from human liver were disrupted in iso-osmotic sucrose and subjected to low-speed centrifugation. The supernatant was layered on a linear sucrose-density gradient in the Beaufay small-volume automatic zonal rotor. The following organelles, with equilibrium densities (g/ml) and principal marker enzyme shown in parentheses, were resolved: plasma membrane (1.12-1.14; 5′-nucleotidase); lysosomes (1.15-1.20; N-acetyl-beta-glucosaminidase); mitochondria (1.20; malate dehydrogenase); endoplasmic reticulum (1.17-1.21; neutral alpha-glucosidase); peroxisomes (1.22-1.24; catalase). 2. The distribution of particulate alkaline phosphatase and, to a lesser degree, leucine 2-naphthylamidase followed that of 5′-nucleotidase. gamma-Glutamyltransferase was associated with membranes of significantly higher equilibrium density than was 5′-nucleotidase. 3. The distribution of 12 acid hydrolases was determined in the density-gradient fractions. beta-Glucosidase had a predominantly cytosolic localization, but the other enzymes showed a broad distribution of activity throughout the gradient. Evidence was presented for two populations of lysosomes with equilibrium densities of 1.15 and 1.20 g/ml, but containing differing amounts of each enzyme. Further evidence of lysosomal heterogeneity was demonstrated by studying the distribution of isoenzymes of hexosaminidase and of acid phosphatase. 4. The resolving power of the centrifugation procedure can be further enhanced with membrane perturbants. Digitonin (0.12 mM) selectively disrupted lysosomes, markedly increased the equilibrium density of plasma-membrane components and lowered the density of the endoplasmic reticulum, but did not affect the mitochondria or peroxisomes. Pyrophosphate (15 mM) selectively lowered the equilibrium density of the endoplasmic reticulum.

scholarly journals The macromolecular properties of blood-group-specific glycoproteins. Characterization of a series of fractions obtained by density-gradient ultracentrifugation

1974 ◽  
Vol 143 (3) ◽  
pp. 669-679 ◽  
Author(s):  
K. Ramakrishnan Bhaskar ◽  
J. Michael Creeth
Keyword(s):  
Density Gradient ◽  
Blood Group ◽  
Buoyant Density ◽  
Physicochemical Characterization ◽  
Cyst Fluid ◽  
Equilibrium Density ◽  
Density Gradient Ultracentrifugation ◽  
Molecular Weights ◽  
Molar Ratios ◽  
Blood Group Substances

1. Equilibrium density-gradient ultracentrifugation in caesium salts was used in two stages in the isolation and subfractionation of the glycoprotein component from a human ovarian-cyst fluid. The eight main subfractions thus obtained were the subject of detailed physicochemical characterization. 2. The fractions were unimodal in buoyant-density distribution, but had discrete ρ0 values ranging from 1.31 to 1.35. 3. Weight-average molecular weights and sedimentation coefficients decreased regularly with decreasing density of the fraction, whereas the partial specific volumes and selective solvation parameters increased. The latter behaviour correlates well with the increasing peptide content of the lighter fractions. 4. The fractions exhibited a range of analytical composition, although all were within the limits previously observed for blood-group substances of Lea specificity. All fractions had approximately equal Lea activity. The peptide content varied systematically from 7% for the densest fraction to 15% for the lightest, but the relative distributions of the amino acids remained essentially constant throughout the series. In particular, serine plus threonine plus proline made up about 50% of the peptide content of all the fractions. Fucose, galactose and N-acetylglucosamine contents decreased with increasing peptide content of the fractions, but N-acetylgalactosamine and sialic acid exhibited the opposite trend. Molar ratios of N-acetylgalactosamine to the sum of serine and threonine remained essentially constant at 0.8–0.9, implying a high degree of glycosylation of all the molecules, but the ratio of N-acetylglucosamine to N-acetylgalactosamine decreased steadily with increasing peptide content, suggesting the presence of oligosaccharide side chains of various lengths. The results are discussed in terms of the accepted structure of glycoprotein molecules. 5. Experiments on the glycoproteins extracted with phenol from the same cyst fluid have confirmed that equilibrium centrifugation in caesium salts does not remove any non-covalently bound protein nor cause any changes in the tertiary structures of these glycoprotein molecules.

scholarly journals STRUCTURE OF TYPE 5 ADENOVIRUS

1963 ◽  
Vol 118 (2) ◽  
pp. 295-306 ◽  
Author(s):  
Wesley C. Wilcox ◽  
Harold S. Ginsberg
Keyword(s):  
Virus Particle ◽  
Density Gradient ◽  
Infectious Virus ◽  
Relative Proportion ◽  
Specific Antigen ◽  
Equilibrium Density ◽  
Virus Particles ◽  
Infected Cells ◽  
Specific Antigens ◽  
Virus Antigens

Type 5 adenovirus was purified by fluorocarbon (freon 113) treatment followed by banding in a CsCl equilibrium density gradient. This method permitted separation of virus from normal host cell materials and virus-specific soluble antigens. Virus banded in CsCl with a mean bouyant density of 1.3349 gm/cm3. The three virus-specific soluble antigens (group- and type-specific antigens and toxin) banded together with a mean bouyant density of 1.2832 gm/cm3. The group-specific antigen was the predominant antigen of the purified virus particle, whereas the group- and type-specific antigens were present in equal titers in the antigen band. Infectious virus particles were inactivated by prolonged dialysis at pH 10.5. Centrifugation of inactivated virus preparations in a CsCl equilibrium density gradient resulted in separation of virus DNA from specific antigen: the antigens banded with a mean bouyant density of 1.2832 gm/cm3 and the DNA sedimented to the bottom of the tube. The predominant antigen derived from purified virus particles was the group-specific antigen and it was in the same relative proportion to the type-specific antigen as measured in intact particles. The antigens derived from disrupted virus were immunologically identical with the soluble virus antigens present in infected cells.

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