title: Improved measurement of the rotor temperature in analytical ultracentrifugation.
abstract: Sedimentation velocity is a classical method for measuring the hydrodynamic, translational friction coefficient of biological macromolecules. In a recent study comparing various analytical ultracentrifuges, we showed that external calibration of the scan time, radial magnification, and temperature is critically important for accurate measurements (Anal. Biochem. 440 (2013) 81-95). To achieve accurate temperature calibration, we introduced the use of an autonomous miniature temperature logging integrated circuit (Maxim Thermochron iButton) that can be inserted into an ultracentrifugation cell assembly and spun at low rotor speeds. In the current work, we developed an improved holder for the temperature sensor located in the rotor handle. This has the advantage of not reducing the rotor capacity and allowing for a direct temperature measurement of the spinning rotor during high-speed sedimentation velocity experiments up to 60,000rpm. We demonstrated the sensitivity of this approach by monitoring the adiabatic cooling due to rotor stretching during rotor acceleration and the reverse process on rotor deceleration. Based on this, we developed a procedure to approximate isothermal rotor acceleration for better temperature control.
authors: Dynamics of Macromolecular Assembly Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Huaying
authors: H
authors: Zhao
authors: Bioengineering and Physical Science Shared Resource, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Andrea
authors: A
authors: Balbo
authors: Mechanical Design and Fabrication, Division of Scientific Equipment and Instrumentation, Office of Research Services, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Howard
authors: H
authors: Metger
authors: Mechanical Design and Fabrication, Division of Scientific Equipment and Instrumentation, Office of Research Services, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Robert
authors: R
authors: Clary
authors: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: rodolfo.ghirlando@nih.gov.
authors: Rodolfo
authors: R
authors: Ghirlando
authors: Dynamics of Macromolecular Assembly Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: schuckp@mail.nih.gov.
authors: Peter
authors: P
authors: Schuck
mesh_terms: D013696:Temperature; D013997:Time Factors; D014461:Ultracentrifugation
keywords: Sedimentation velocity; Temperature calibration