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Is the molten globule a third thermodynamic state of protein? The example of α‐lactalbumin
Author(s) -
Pfeil Wolfgang
Publication year - 1998
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/(sici)1097-0134(19980101)30:1<43::aid-prot4>3.0.co;2-l
Subject(s) - molten globule , chemistry , calorimetry , alpha lactalbumin , isothermal microcalorimetry , titration , thermodynamics , lactalbumin , heat capacity , isothermal titration calorimetry , differential scanning calorimetry , circular dichroism , crystallography , enthalpy , chromatography , physics
Thermal and denaturant‐induced transitions of the acid molten globule state of bovine α‐lactalbumin (acid [A] state) are analyzed by scanning calorimetry, titration calorimetry, viscosimetry, and derivative spectroscopy. A denaturant‐induced heat effect of the A state is shown by a calorimetric difference titration of the A‐state versus unfolded (reduced) α‐lactalbumin. However, changes of viscosity and derivative spectra do not parallel the heat effect. At thermal denaturation monitored by derivative spectroscopy and scanning microcalorimetry the presence of a gradual transition in α‐lactalbumin A state is shown. The results are consistent with the existence of tertiary interactions in the A state and the absence of a cooperative unfolding transition of the molten globule. The results do not support the idea that the molten globule is a third thermodynamic state. Proteins 30:43–48, 1998. © 1998 Wiley‐Liss, Inc.