title: Self-Association of Apo A-1 Studied with Dynamic and Static Light Scattering.
abstract: Static and dynamic light scattering were employed to determine simultaneously the average relative molecular mass, Mr, and the average hydrodynamic radius, Rh, of protein molecules. The new method was applied to the association-dissociation equilibrium of apolipoprotein A-1 (Apo A-1) and its thermal unfolding. As a control, lysozyme was measured as a nonassociating protein. Apo A-1 forms oligomers as a function of concentration and temperature, and the equilibrium can be described by a cooperative association model, consisting of a nucleation step and a growth step. At concentrations of 1 and 2.7 mg/mL, the Apo A-1 solution contained mainly monomers and octamers, with intermediates occurring at very low concentrations. Oligomer formation was maximal at 22 °C and was characterized by a temperature-dependent association constant. The cooperative association model allows the quantitative analysis of both the average relative molecular mass, Mr, and the average hydrodynamic radius, Rh, with the same set of model parameters which, in turn, are also applicable to analytical ultracentrifugation experiments. The light scattering experiments were reversible as long as the Apo A-1 solution was not heated above 60 °C.
authors.affiliation: Schönfeld-Protein Science Consulting , Marienmattenweg 7, D-79115 Freiburg, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Schönfeld
authors.affiliation: Wyatt Technology Europe GmbH , Hochstraße 12a, DE-56307 Dernbach, Germany.
authors.forename: Dierk
authors.initials: D
authors.lastname: Roessner
authors.affiliation: Biozentrum, University of Basel , Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Seelig
mesh_terms: D016632:Apolipoprotein A-I / Q000737:chemistry*; D000067493:Dynamic Light Scattering; D006801:Humans; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry; D013696:Temperature
chemical_list: D016632:Apolipoprotein A-I; D011994:Recombinant Proteins