title: Temperature-dependent phase transitions in zeptoliter volumes of a complex biological membrane.
abstract: Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50-60 °C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 ± 5 °C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.
authors.affiliation: The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Maxim P
authors.initials: MP
authors.lastname: Nikiforov
authors.forename: Sophia
authors.initials: S
authors.lastname: Hohlbauch
authors.forename: William P
authors.initials: WP
authors.lastname: King
authors.forename: Kislon
authors.initials: K
authors.lastname: Voïtchovsky
authors.forename: Sonia Antoranz
authors.initials: SA
authors.lastname: Contera
authors.forename: Stephen
authors.initials: S
authors.lastname: Jesse
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kalinin
authors.forename: Roger
authors.initials: R
authors.lastname: Proksch
mesh_terms: D008832:Microchemistry; D018625:Microscopy, Atomic Force; D044367:Phase Transition; D018717:Purple Membrane / Q000737:chemistry* / Q000648:ultrastructure; D013696:Temperature