PARTITION OF MACROMOLECULES IN AQUEOUS TWO-PHASE SYSTEMS 39 



dextran-polyethylene glycol system may be found in refs. [3] and [16]. 

 The dextran-polyethylene glycol system is useful in the countercurrent 

 distribution of proteins [17, 18]. The settling time of this system may be 

 as short as 5-10 minutes. A countercurrent distribution experiment [18] 

 with a partly purified preparation of ceruloplasmin is recorded in Fig. 5. 

 The enzyme activity curve is almost identical with the theoretical curve 

 indicating that the enzyme activity is associated with a single component. 

 Most experiments indicate that proteins partition according to the Nernst 

 partition law in the dextran-polyethylene glycol system, that is, the value 

 of the partition coefficient is independent of the protein concentration and 

 the presence of other proteins. This phase system may therefore be used 

 for characterization and fractionation of proteins. 



References 



1. Tavel, P., and Signer, R., "Advances in Protein Chemistry" II, 237 Academic 

 Press, New York (1956). 



2. Craig, L. C, in "A Laboratory Manual of Analytical Methods of Protein 

 Chemistry", Vol. i, ed. P. Alexander and K. J. Block. Pergamon Press, 

 Oxford, 121 (i960). 



3. Albertsson, P. -A., " Partition of Cell Particles and Macromolecules ". Almqvist 

 & Wiksell, Stockholm; John Wiley &; Sons, Inc., New York (i960). 



4. Dobry, A., and Boyer-Kawenoki, F., ^. Polym. Sci. 2, 90 (1947). 



5. Albertsson, P. -A., and Frick, G., Biocliim. biophys. Acta 37, 230 (i960). 



6. Frick, G., and Albertsson, P. -A., Nature, Land. 183, 1070 (1959). 



7. Wesslen, T., Albertsson, P. -A., and Philipson, L., Arch. Virusforsch. 9, 510 



(1959)- 



8. Philipson, L., Albertsson, P. -A., and Frick, G., J^irology ll, 553 (i960). 



9. Norrby, E., and Albertsson, P. -A., Nature, Loud. 188, 1047 (i960). 



10. Frick, G., Exp. Cell Res. (in press). 



11. Lif, T., Frick, G., and Albertsson, P. -A., to be published. 



12. Tanford, C, " S\Tnposium on Protein Structure", ed. A. Neuberger. Methuen 

 & Co. Ltd., London; John Wiley &: Sons, Inc., New York, 35 (1958). 



13. Yang, J. T., and Foster, J. F.,jf. Amer. cheni. Soc. 76, 1588 (1954). 



14. Sterman, M., and Foster, J. F., J. Amer. che?n. Soc. 78, 3652 (1956). 



15. Foster, J. F., in Putnam, F. W., "The Plasma Proteins", Vol. i. Academic 

 Press, New York, i (i960). 



16. Albertsson, P. -A., and Nyns, E. J., Ark. Kemi 17, 197 (1961). 



17. Albertsson, P. -A., and Nyns, E. J., Nature, Loud. 184, 1465 (1959). 



18. Broman, L., and Albertsson, P. -A., to be published. 



Discussion 



HiRs: Have there been any studies on the rate at which equilibrium has been 

 obtained with some of these systems ? 



Albertsson: We haven't studied this systematically but it appears that just a 

 few inversions are enough to get an equilibrium. 



Theorell: How is the separation of these materials from the polymers 

 achieved ? 



