ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Human transferrin was examined by analytical density gradient equilibrium centrifugation using a short liquid column and employing an iodinated organic gradient salt. Favorable conditions of low pressure and relatively low ionic strength could therefore be obtained. The short liquid column also permitted the layering of extra salt solution above the protein solution in a liquid equalization stage of each experiment. In this stage the amount of preferentially bound water was determined by measurement of solvation arising from the dissolution of the protein which had been added to the centrifuge cell as freeze-dried material. Since schlieren optics were employed, the refractive index of the macromolecular component in the mixed solution had to be known. This quantity was determined from the refractive index difference of the solvent/solution boundary at the liquid equalization stage of each experiment or, alternatively, by regression analysis of the equilibrium data. The new regression method yielded an anhydrous molecular weight of 78,000 daltons which is the same as the value obtained by the classical density gradient equilibrium method performed under the same conditions. Control experiments showed that the analytical ultracentrifuge cell cannot be regarded as a closed, inert system.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1977.180150413
