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The Partial Specific Volume of P-Lactoglobulin A in Aqueous Urea Solutions

S. Lapanje ; Department of Chemistry, University of Ljubljana, Ljubljana, Slovenia, Yugoslavia
J. Škerjanc ; Department of Chemistry, University of Ljubljana, Ljubljana, Slovenia, Yugoslavia
V. Doleček ; Department of Chemistry, University of Ljubljana, Ljubljana, Slovenia, Yugoslavia

Sažetak

The partial specific volume of ~-lactoglobulin A in 0.02 M
NaCl - 0.01 M HCl containing different amounts of urea has
been determined from density measurements. The partial specific
volume first increases with urea concentration, reaches a maximum,
decreases, reaches a minimum, and then increases again.
In the interpretation of this behavior, the binding of urea to
the protein and the imperfect atomic packing in native protein
molecules have been assumed to be the dominant factors. From
dilatometric experiments the differences between the partial
molar volume of the protein in 0.02 M NaCl-0.01 M HCl with
and without urea have been obtained. The values of the differences
agree satisfactorily with those calculated from the partial
specific volume. Furthermore, the volumes as well as their changes
reflect the interaction of urea with the protein. Dilatometric
experiments were also performed with the protein in 0.02 M NaCl
to which urea was added. Comparison of the obtained results
with those in 0.02 M NaCl-0.01 M HCl displays the fact that
the partial specific volume is pH-dependent.

Ključne riječi

Hrčak ID:

197336

URI

https://hrcak.srce.hr/197336

Datum izdavanja:

20.4.1971.

Posjeta: 708 *