Thermodynamics of thermal unfolding of bovine apo-alpha-lactalbumin.


Abstract

Thermal unfolding of bovine alpha-lactalbumin in 10 mM borate buffer at pH 8.0 in the presence of 0.01-1.0 M NaCl was studied in terms of CD ellipticity. The apoprotein changes the conformation from a native-like (N) to an unfolded (U) form, which has an appreciable amount of the secondary structure but no tertiary structure, in the two-state type. Various thermodynamic parameters of the transition were analyzed. The differences in enthalpy and heat capacity between the N and U states are similar to the corresponding differences of the holoprotein obtained with the calorimetric method by Pfeil. It is shown that one Na+ binds with a binding constant larger than 10(2)-10(3) M-1 to a specific site (probably to the Ca2+-binding site) in the molecule and the bound Na+ stabilizes the N form of the apoprotein. Study holds ProTherm entries: 11714, 11715, 11716, 11717 Extra Details: Apo. bovine apo-alpha-lactalbumin; Na+binding; thermal unfolding

Submission Details

ID: 2WTPVyXG3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:42 p.m.

Version: 1

Publication Details
Hiraoka Y;Sugai S,Int. J. Pept. Protein Res. (1984) Thermodynamics of thermal unfolding of bovine apo-alpha-lactalbumin. PMID:6735592
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