Separation of Racemate from Excess Enantiomer of Chiral Nonracemic Compounds via Density Gradient Ultracentrifugation

2008 ◽  
Vol 130 (8) ◽  
pp. 2426-2427 ◽  
Author(s):  
Yitzhak Mastai ◽  
Antje Völkel ◽  
Helmut Cölfen
Keyword(s):  
Density Gradient ◽  
Density Gradient Ultracentrifugation

scholarly journals Isolation of human synovial-fluid hyaluronate by density-gradient ultracentrifugation and evaluation of its protein content

1972 ◽  
Vol 126 (5) ◽  
pp. 1073-1080 ◽  
Author(s):  
Irwin Scher ◽  
David Hamerman
Keyword(s):  
Synovial Fluid ◽  
Density Gradient ◽  
Density Gradient Ultracentrifugation ◽  
Proteolytic Digestion ◽  
Peptide Fragments ◽  
Guanidinium Chloride ◽  
Caesium Chloride ◽  
Normal Human ◽  
Protein Moiety ◽  
Human Synovial Fluid

1. A compound of hyaluronate and protein, called hyaluronate–protein was isolated from pooled human synovial fluids by caesium chloride density-gradient ultracentrifugation. 2. The isolated hyaluronate–protein was labelled with [125I]iodide and the following studies were done. (a) Ultracentrifugation in caesium chloride showed that the protein moiety (125I counts) and hyaluronate (hexuronate) sedimented together in the middle of the gradient. (b) The labelled hyaluronate–protein was treated with trypsin, and ultracentrifugation showed that peptide fragments (125I counts) were dispersed throughout the gradient, indicating proteolytic digestion. Hyaluronate sedimented in the middle of the gradient. (c) The labelled hyaluronate–protein was digested with streptococcal hyaluronidase, and ultracentrifugation showed that hyaluronate fragments were dispersed throughout the gradient, indicating digestion of the polysaccharide. The protein moiety, without attached hyaluronate, now sedimented at the top of the gradient. (d) Ultracentrifugation of labelled hyaluronate–protein in 4m-guanidinium chloride showed that protein and hyaluronate sedimented together. 3. These studies confirm that hyaluronate is combined with a small quantity of protein in normal human synovial fluid. A mild method for the rapid isolation of hyaluronate–protein in good yield is described.

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.

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