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
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:42 p.m.
|Number of data points||6|
|Proteins||Alpha-lactalbumin ; Alpha-lactalbumin|
|Assays/Quantities/Protocols||Experimental Assay: dCp ionic:KCl: 0.1 M, pH:6.8, buffers:phosphate: 10-20 mM ; Experimental Assay: dCp buffers:imidazole-HCl: 40 mM, ionic:: , pH:6.3 ; Experimental Assay: dHvH buffers:imidazole-HCl: 40 mM, ionic:: , pH:6.3 ; Experimental Assay: dCp buffers:borate: 10 mM, ionic:NaCl: 0.01-1.0 M, pH:8.0 ; Experimental Assay: dHvH buffers:borate: 10 mM, ionic:NaCl: 0.01-1.0 M, pH:8.0|
|Libraries||Mutations for sequence MEQLTKCEVFRELKDLKGYGGVSLPEWVCTTFHTSGYDTQAIVQNNDSTEYGLFQINNKIWCKDDQNPHSSNICNISCDKFLDDDLTDDIVCVKKILDKVGINYWLAHKALCSEKLDQWLCEKL|