Compactness of the kinetic molten globule of bovineα‐lactalbumin: A dynamic light scattering study

During folding of globular proteins, the molten globule state was observed as an equilibrium intermediate under mildly denaturing conditions as well as a transient intermediate in kinetic refolding experiments. While the high compactness of the equilibrium intermediate ofα‐lactalbumin has been verif...

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Bibliographic Details
Published in:Protein science 1998-09, Vol.7 (9), p.2004-2011
Main Authors: Gast, Klaus, Zirwer, Dietrich, MÜller‐Frohne, Marlies, Damaschun, Gregor
Format: Article
Language:English
Subjects:
Animals
Cattle
Circular Dichroism
Diffusion
dynamic light scattering
hydrophobic collapse
Kinetics
Lactalbumin - chemistry
molecular compactness
molten globule
Protein Conformation
Protein Folding
Scattering, Radiation
α‐lactalbumin
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Summary:During folding of globular proteins, the molten globule state was observed as an equilibrium intermediate under mildly denaturing conditions as well as a transient intermediate in kinetic refolding experiments. While the high compactness of the equilibrium intermediate ofα‐lactalbumin has been verified, direct measurements of the compactness of the kinetic intermediate have not been reported until now. Our dynamic light scattering measurements provide a complete set of the hydrodynamic dimensions of bovineα‐lactalbumin in different conformational states, particularly in the kinetic molten globule state. The Stokes radii for the native, kinetic molten globule, equilibrium molten globule, and unfolded states are 1.91, 1.99, 2.08, and 2.46 nm, respectively. Therefore, the kinetic intermediate appears to be even more compact than its equilibrium counterpart. Remarkable differences in the concentration dependence of the Stokes radius exist revealing strong attractive but repulsive intermolecular interactions in the kinetic and equilibrium molten globule states, respectively. This underlines the importance of extrapolation to zero protein concentration in measurements of the molecular compactness.
ISSN:0961-8368
1469-896X
DOI:10.1002/pro.5560070917