title: Low density lipoproteins as circulating fast temperature sensors.
abstract: BACKGROUND
  The potential physiological significance of the nanophase transition of neutral lipids in the core of low density lipoprotein (LDL) particles is dependent on whether the rate is fast enough to integrate small (+/-2 degrees C) temperature changes in the blood circulation.
  
  
  RESULTS
  Using sub-second, time-resolved small-angle X-ray scattering technology with synchrotron radiation, we have monitored the dynamics of structural changes within LDL, which were triggered by temperature-jumps and -drops, respectively. Our findings reveal that the melting transition is complete within less than 10 milliseconds. The freezing transition proceeds slowly with a half-time of approximately two seconds. Thus, the time period over which LDL particles reside in cooler regions of the body readily facilitates structural reorientation of the apolar core lipids.
  
  
  CONCLUSIONS
  Low density lipoproteins, the biological nanoparticles responsible for the transport of cholesterol in blood, are shown to act as intrinsic nano-thermometers, which can follow the periodic temperature changes during blood circulation. Our results demonstrate that the lipid core in LDL changes from a liquid crystalline to an oily state within fractions of seconds. This may, through the coupling to the protein structure of LDL, have important repercussions on current theories of the role of LDL in the pathogenesis of atherosclerosis.
authors.affiliation: Institute of Biophysics and Nanosystems Research, Austrian Academy of Sciences, Graz, Austria. ruth.prassl@oeaw.ac.at
authors.forename: Ruth
authors.initials: R
authors.lastname: Prassl
authors.forename: Magdalena
authors.initials: M
authors.lastname: Pregetter
authors.forename: Heinz
authors.initials: H
authors.lastname: Amenitsch
authors.forename: Manfred
authors.initials: M
authors.lastname: Kriechbaum
authors.forename: Robert
authors.initials: R
authors.lastname: Schwarzenbacher
authors.forename: John M
authors.initials: JM
authors.lastname: Chapman
authors.forename: Peter
authors.initials: P
authors.lastname: Laggner
mesh_terms: D002152:Calorimetry, Differential Scanning; D008077:Lipoproteins, LDL / Q000097:blood* / Q000737:chemistry; D008954:Models, Biological; D013696:Temperature
chemical_list: D008077:Lipoproteins, LDL