A new general method for the assessment of the molecular-weight distribution of polydisperse preparations. Its application to an intestinal epithelial glycoprotein and two dextran samples, and comparison with a monodisperse glycoprotein.
A specimen of intestinal glycoprotein isolated from the pig and two samples of dextran, all of which are polydisperse (that is, the preparations may be regarded as consisting of a continuous distribution of molecular weights), have been examined in the ultracentrifuge under meniscus-depletion conditions at equilibrium. They are compared with each other and with a glycoprotein from Cysticercus tenuicollis cyst fluid which is almost monodisperse. The quantity c(-(1/3)) (c=concentration) is plotted against xi (the reduced radius); this plot is linear when the molecular-weight distribution approximates to the ;most probable', i.e. when M(n):M(w):M(z): M((z+1))....... is as 1:2:3:4: etc. The use of this plot, and related procedures, to evaluate qualitatively and semi-quantitatively molecular-weight distribution functions where they can be realistically approximated to Schulz distributions is discussed. The theoretical basis is given in an Appendix.
D000818:Animals; D003551:Cysticercosis; D003911:Dextrans / Q000032:analysis*; D006023:Glycoproteins / Q000032:analysis*; D007421:Intestine, Small / Q000032:analysis; D008433:Mathematics; D008722:Methods; D008956:Models, Chemical; D008970:Molecular Weight; D011336:Probability; D013552:Swine; D014461:Ultracentrifugation
D003911:Dextrans; D006023:Glycoproteins