Ultracentrifugation studies

It has been found possible to fractionate palladium-polyvinyl alcohol catalysts into more and less active fractions by applying ultracentrifugation (10). It is believed that this fractionation is the result of the heavier palladium particles being deposited while the lighter ones remain sus- 

Electron micrographs have provided additional information available about the palladium-polyvinyl alcohol catalysts. As has been mentioned, they established that palladium chloride is reduced to palladium in the presence of an aqueous suspension of polyvinyl alcohol. Further electron micrographs established that the palladium (12) and also rhodium are 

A variety of compounds has been reduced employing colloidal palladium catalysts supported by synthetic polymers. Table I summarizes the results of various reductions (13). 

Compound Catalyst Moles H2 Mole Cpd. Duration of Reaction Products 

Cinnamic aldehyde (5.075 g.) Pd-PAME/ 2.31 10 hr. / Hydrocinnamic aldehyde 4 Hydrocinnamic alcohol 

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Data obtained for purified hemocyanin samples in pH 9.6 glycine buffer at various levels of free calcium ion are summarized in Table I. The apparent protein equilibrium (formation) constant Kp (D = dodec-amer or whole molecules and H = hexamer or half molecules) and the degree of dissociation by weight, a, are taken from the ultracentrifuge study of Morimoto and Kegeles (12). 

The authors are grateful to their colleague L. B. Barnett, for assistance with ultracentrifuge studies and to Blanche Hall and Barbara Greenberg for excellent technical assistance. This work was supported by a grant from the Bio-Research Center Company, Ltd. 

R.H. Ottewill, C.C. Storer and T. Walker, Ultracentrifugal study of a nonionic surface-active agent in D2O, Trans. Faraday Soc. 63 (1967) 2796-2802. 

Steinberg IZ, Schachman HK (1966) Ultracentrifugation Studies with Absorption Optics, V, Analysis of Interacting Systems Involving Macromolecules and Small Molecules. Biochemistry 5(12) 3728... 

Jensen, R. H., and N. Davidson Spectrophotometric, potentiometric, and density gradient ultracentrifugation studies of the binding of silver ion by DNA. Biopolymers 4, 17 (1966). 

A large series of ultracentrifugation studies of normal and pathological gastric juices has been recently reported by Hartmann et al. (Hla). The presence of 4 components having different sedimentation constants was ascertained, as well as that of many other complexes of glycoproteins, enzymes, and polypeptides. 

Nash AM and Wolf WJ. Solubility and ultracentrifugal studies on soybean globulins. Cereal Chem. 1967 44 183-192. 

The molecular weight of a protein or other macromolecule can be obtained from ultracentrifugation studies. The principles involved are rather simple a high-molecular-weight molecule sediments faster and diffuses slower than a lower-molecular-weight molecule of the same density. This is expressed in the Svedberg equation ... 

Richard AJ. Ultracentrifugal study of effect of sodium chloride on micelle size of fusidate sodium. / Pharm Sci 1975 64 873-875. 

Pedersen, K. O. Ultracentrifugal Studies on Scrum and Serum Fractions. 

The structural transition from inverted to normal micellar structure occurs around 0.8 to 0.7 water mass fraction. It is obviously a progressive transition. The microstructure in this region is not yet well established. The ultracentrifuge study has shown that the inverted micellar structure may exist persistently down to 0.8 water mass fraction. But the quasielastic light scattering has detected the trace of normal micellar structure as low as 0.7 water mass fraction (5). 

In any centrifugation study with humic substances the suppression of intermolecular charge repulsion by the addition of electrolyte is essential (Cameron et al., 1972b Hayes and Swift, 1978). Any ultracentrifugation studies, analytical or preparative, where this has not been property done should be disregarded. 

Most ultracentrifuge studies of humic substances have used the sedimentation-velocity method. Flaig et al. (1975) have reviewed this work. In general, the results of this work indicated that all the solutions studied were polydisperse as we have discussed previously, in a polydisperse system, the ordinary sedimentation-velocity equation cannot be applied because each different particle size has a different diffusion coefficient and different sedimentation constant. 

Ultracentrifugal studies as to the homogeneity of this fraction were unsatisfactory because of the limitations of materials. No final statement can, therefore, be made concerning the molar proportions of zinc to protein, pending establishment of the molecular weight. However, the minimum molecular weight based on zinc content would be 21,700. The magnitude of the zinc content is comparable to that encountered in other metallopro-teins (Tables I, II). The isoelectric point was found close to pH 6.5. 

Figure 10.5 Ultracentrifugation studies of ATCase. Sedimentation velocity patterns of (A) native ATCase and (B) the enzyme after treatment with p-hydroxymercuribenzoate show that the enzyrne can be dissociated into regulatory (r) and catalytic (c) subunits, [After J. C Gerhart and H. K. Schachman, 6/ochem/sfry 4(1965) 1054-1062.]...

W3. Wallenius, G., Trautman, R., Kunkel, H. G., and Franklin, E. C., Ultracentrifugal studies of major non-lipide electrophoretic components of normal serum. J. Biol. Chem. 226, 253-267 (1957). 

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