ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The compositional buoyant densities, ρ00;, of human γ-immunoglobulin, bovine serum mercaptalbumin, and egg albumin have been measured in CsCl solutions in the analytical ultracentrifuge as a function or pressure. Standard pressure coefficients, ψ0, and standard partial specific volumes of the solvated proteins, υ0S,0, have been computed from these data. The ψ0 values obtained are strikingly different from each other and from the only other pressure coefficients which have been measured, those values obtained for nucleic acids and nucleoproteins. The ψ value for γ-immunoglobulin is negative, the first nonpositive value obtained, and suggests an unusual internal structure for this protein. The pressure coefficient of mercaptalbumin is not constant. A second-order relation is derived and utilized to interpret these data. The slope of the ρ00(P) plot for egg albumin was constant and negative and yielded values of ψ0 which are about 20% as large as those reported for DNA. Evaluation of published isopiestic data for egg albumin in CsCl solutions provided the dependence of preferential hydration on water activity. This quantity, (dΓ′/da00) as well as α, were found to be negative. The values of ψ0 and α were used to compute the effective density gradient from which the correct molecular weight of egg albumin was obtained. The apparent specific volume of egg albumin in a buoyant CsCl solution was measured using the Mettler-Paar densimeter.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1978.360170402
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