Ultracentrifugal sedimentation

Ultracentrifugally sedimented micelles have a hydration of 1.6-2.7g H2Og 1 protein but voluminosities of 3-7mlg-1 have been found by viscosity measurements and calculation of specific hydrodynamic volumes. These values suggest that the micelle has a porous structure in which the protein occupies about 25% of the total volume. 

Using the ultracentrifuge sedimenting method, Gralen and Svedberg [40] have determined the molecular weight of nitrocellulose prepared from various types of cellulose. The nitration was carried out at 0°C by means of a mixture composed of 40% of nitric acid, 40% of phosphoric acid, and 20% of phosphorus pentoxide. The results are collected in Table 79. 

Morr, C. V. 1965. Effect of heat upon electrophoresis and ultracentrifugal sedimentation properties of skimmilk protein fractions. J. Dairy Sci. 48, 8-13. 

The enzyme from M. audouini cultured on wheat bran, initially called AMP deaminase (185), has been extensively purified (4000-fold) (188) and renamed ATP aminohydrolase because of greater activity on that substrate. The ultracentrifugal sedimentation pattern exhibited a large and small peak, but no evidence was presented regarding the identity of either. Requirements for catalytic cofactors were negative. 

Horse serum Bacteria, 317,000 Ultracentrifugation sedimentation equilibrium T3... 

Analytical Ultracentrifugation. Sedimentation coefficients were determined with an ultracentrifuge (Beckman L8-70M) fitted with a schlieren analytical attachment. Photographic images of schlieren (refractive index gradient) profiles were analyzed with a profile projector (Nikon, model VI0) using standard procedures (13). 

If the macromolecules are forced by some external agency to flow with a velocity V, light scattering can be used to measure this velocity. There are several possible examples of this (a) macromolecules suspended in a fluid which is in uniform motion with velocity Y, (b) macromolecules falling at their terminal velocities in a viscous solvent under the action of gravity (sedimentation velocity), (c) macroions accelerated to a terminal velocity by an externally imposed electric field (electrophoresis), and (d) macromolecules accelerated to their terminal velocity in an ultracentrifuge (sedimentation velocity). 

Particle size Electron microscopy, light scattering, ultracentrifugal sedimentation, light microscopy... 

---