Using magnetic nanoparticles to probe protein damage in ferritin caused by freeze concentration

We demonstrate a method for monitoring the damage caused to a protein during freeze-thawing in the presence of glycerol, a cryo-protectant. For this work we synthesized magnetite nanoparticles doped with 2.5% cobalt inside the protein ferritin (CMF), dissolved them in different concentration glycero...

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Bibliographic Details
Published in:AIP advances 2015-11, Vol.5 (11), p.117201-117201-5
Main Authors: Chagas, E. F., Correia Carreira, S., Schwarzacher, W.
Format: Article
Language:English
Subjects:
Ferritin
Glycerol
Magnetic measurement
Magnetization
Nanoparticles
Photon correlation spectroscopy
Proteins
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Summary:We demonstrate a method for monitoring the damage caused to a protein during freeze-thawing in the presence of glycerol, a cryo-protectant. For this work we synthesized magnetite nanoparticles doped with 2.5% cobalt inside the protein ferritin (CMF), dissolved them in different concentration glycerol solutions and measured their magnetization after freezing in a high applied field (5 T). As the temperature was raised, a step-like decrease in the sample magnetization was observed, corresponding to the onset of Brownian relaxation as the viscosity of the freeze-concentrated glycerol solution decreased. The position of the step reveals changes to the protein hydrodynamic radius that we attribute to protein unfolding, while its height depends on how much protein is trapped by ice during freeze concentration. Changes to the protein hydrodynamic radius are confirmed by dynamic light scattering (DLS) measurements, but unlike DLS, the magnetic measurements can provide hydrodynamic data while the solution remains mainly frozen.
ISSN:2158-3226
2158-3226
DOI:10.1063/1.4935261